Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1002/ejoc.202301130

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Authorship：Last author,　Corresponding author   Publishing type：Research paper (scientific journal)  

DOI： 10.3390/chemistry5040177

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

In this work, a straightforward synthesis of C3-N1' bisindolines is achieved by a formal umpolung strategy. The protocols were tolerant of a wide variety of substituents on the indole and indoline ring. In addition, the C3-N1' bisindolines could be converted to C3-N1' indole-indolines and C3-N1'-bisindoles. Also, we have successfully synthesized (±)-rivularin A through a biomimetic late-stage tribromination as a key step.

DOI： 10.1002/chem.202302963

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1021/acs.joc.3c00691

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society (ACS)  

DOI： 10.1021/acs.joc.3c00013

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：MDPI AG  

C3–N1′ bond formation of bisindoles has been a great challenge due to the intrinsic reactivity of indoles as both C3 and N1-nucleophilic character. Herein, we demonstrate an C3–N1′ cross-coupling reaction of indoles using N-methoxyindoles as N-electrophilic indole reagents in the presence of Lewis acid. The bisindoles generated in this transformation are latent C3-nucleophile, allowing them to be used as strategic intermediates in sequential C3–N1′–C3′–N1″ triindole formations. The potential synthetic usefulness of this sequential transformation was highlighted upon application to the construction of C3–N1 looped polyindoles.

DOI： 10.3390/chemistry5010033

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Authorship：Last author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.3390/IJMS24054411

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society (ACS)  

DOI： 10.1021/acs.joc.2c02561

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DOI： 10.1039/D3RA90053C

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：MDPI AG  

(1) Background: Japanese Kampo medicine has its origin in ancient Chinese medicine. In 742, a Tang Dynasty monk named Jianzhen (Ganjin) was invited by Japanese clerics to visit Japan and teach commandments in Buddhism. Because of the dangers of the voyage and also other obstacles, he took 11 years to reach Japan on the sixth voyage and he was blind when he arrived in Japan. He was the first person in China to go to Japan to establish the Buddhism commandments, and he was also the first person in Japan to directly teach traditional Chinese medicine. Until now, there have been few reports in English about the details of the Chinese herbal medicines he brought to Japan, including the types of herbal medicines, pharmacological activities, and formulations. In the review, we systematically and comprehensively summarized Jianzhen’s life from the standpoint of his medical and pharmaceutical knowledge and the types and pharmacological activities of Chinese herbal medicines and prescriptions that were brought to Japan by Jianzhen; (2) Methods: A review was made on the relevant literature written by Chinese, Japanese, and English languages regarding the medical and pharmacological knowledge of Jianzhen, the 36 Chinese herbal medicines brought to Japan by Jianzhen, and the pharmacological and therapeutic effects of these 36 herbal medicines, as well as their formulations; (3) Results: The review of the literature proved that Jianzhen’s prescriptions served as a basis for current herbal medicines (Kampo) in Japan. In the process of the literature search, we found a book entitled Jianshangren (Holy Priest Jianzhen)’s Secret Prescription, which recorded the complete prescription of the 36 traditional Chinese medicines Jianzhen brought to Japan; (4) Conclusions: Jianzhen is one of the ancestors of traditional Chinese medicine/Kampo medicine, and he brought traditional Chinese medicine and medical books to Japan for patients. He made important contributions to the development of traditional Chinese medicine in Japan.

DOI： 10.3390/compounds2040022

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society ({ACS})  

DOI： 10.1021/acs.jnatprod.2c00559

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Organic & Biomolecular Chemistry  

<jats:p>We would like to take this opportunity to highlight the Outstanding Reviewers for <jats:italic>Organic &amp; Biomolecular Chemistry</jats:italic> in 2021, as selected by the editorial team for their significant contribution to the journal.</jats:p>

DOI： 10.1039/D2OB90069F

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Authorship：Lead author,　Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：Wiley  

DOI： 10.1002/chem.202201113

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Language：English  

DOI： 10.1021/acs.orglett.2c00370

J-GLOBAL

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Royal Society of Chemistry ({RSC})  

We have developed an efficient reaction of 3-azido-2-methoxyindolines with <italic>O</italic>-nucleophiles in the presence of a Lewis acid, affording 2-monoacyloxy or alkoxy indolin-3-ones.

DOI： 10.1039/D2QO00048B

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Royal Society of Chemistry (RSC)  

Use of 3-azidoindoles in organic synthesis remains difficult task owing to their instabilities. Herein, we report a general and concise approach for tackling this problem by using 3-azidoindole surrogates. The...

DOI： 10.1039/d1cc06033c

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We introduce readily available ammonium hemiaminals as O-transfer reagents and commercially available acetonitriles as a primary amide enolate precursor. The combination serves as an amide enolate equivalent, thereby providing one-pot access to α-substituted indolylacetamides. A broad substrate scope and good functional group tolerance as well as gram-scale synthesis make this protocol highly attractive. Mechanistic experiments suggest that the cyano group is trapped by a hydroxy group of hemiaminals en route to the desired primary amides under metal-free conditions.

DOI： 10.1039/d1cc02821a

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

Enamines undergo alpha-indolization with ammonium salts in the presence of Et3N to form alpha-indolylketones. This is the first example of transition metal-, oxidant-, and fluorous solvent-free alpha-indolization of ketones. Key to the success of this convenient protocol was the use ofin situgenerated electrophilic indole species, as well as the use of enamines as a ketone enolate equivalent.

DOI： 10.1039/d0cc04795c

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Authorship：Last author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.14894/faruawpsj.56.8_757

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

<p>One-pot synthesis of indole-fused bicyclo[2.2.2]octanones from DiMeOIN and 2-cyclohexen-1-one are accomplished under iodine catalyst. This simple and metal-free conditions provides a practical tool to construct Csp3-rich complex molecules via oxidative...</p>

DOI： 10.1039/d0ob01038c

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Authorship：Last author,　Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：Royal Society of Chemistry ({RSC})  

DOI： 10.1039/D0CC01210F

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.3987/com-19-s(f)19

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publisher：The Society of Synthetic Organic Chemistry, Japan  

<p>C3-Nucleophilic substitution of indoles has been limited because the transformation requires an umpolung of the C3 position of indoles. Among the indole derivatives, indole-2,3-epoxides could be potentially be used as C3-electrophilic reagents due to the electrophilic nature of the C2 and C3 positions. However, their use as C3 electrophilic reagents has not been possible so far due to their instability.</p><p>We describe a novel and bench stable surrogate of indole-2,3-epoxide, 2-hydroxyindoline-3-triethylammonium bromide (HITAB), which was found to be a convenient reagent for formal C3-electrophilic reactions of indoles with nucleophiles. By taking advantage of the nucleophilic character of the oxygen of the 2-hydroxyindoline, interrupted retro-Claisen and interrupted Feist-Bénary reactions with 1,3-dicarbonyl compounds, one-pot formation of furodiindolines from 3-substituted indoles were achieved. Furthermore, we developed a novel cascade reaction of the indole-2,3-epoxide surrogate with γ-carbolines to access multiheterocyclic compounds containing both isotryptamines and pyrimido［1,6-<i>a</i>］indoles. This reaction utilizes the <i>in situ</i> formation of a bulky quaternary ammonium salt via ammonium exchange, which undergoes Hofmann elimination/vinylogous Mannich/retro-Mannich/cyclization cascade sequences. The synthetic potential of the ammonium salts was demonstrated by the short synthesis of cryptolepine, iheyamine A, racemocine B derivative, and neocryptolepine derivative.</p>

DOI： 10.5059/yukigoseikyokaishi.78.597

CiNii Article

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

The regioselective synthesis of both 2- and 3-alkoxyindoles from a common intermediate, 2-alkoxy-3-bromoindolines (ROBIN), is described. The 2-alkoxyindoles are obtained by a base-promoted regioselective elimination of HBr from ROBIN, whereas the synthesis of 3-alkoxyindoles is achieved by a silver-mediated alkoxylation followed by an acid-promoted elimination of alkoxide. This key elimination features the complete regioselectivity and no need for catalysts, that makes it have potential synthetic applications. Furthermore, this protocol is user friendly because ROBIN is able to be prepared from commercially available indoles and is a bench-stable easy-to-handle crystalline substrate, thus allowing the concise synthesis of a variety of both 2- and 3-alkoxyindoles.

DOI： 10.1248/cpb.c20-00135

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DOI： 10.1039/d0ob01038c

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Publishing type：Research paper (scientific journal)   Publisher：Royal Society of Chemistry ({RSC})  

DOI： 10.1039/D0OB01038C

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© 2019 Georg Thieme Verlag. All rights reserved. We disclose a silver-mediated intramolecular Friedel-Crafts-type cyclization of 2-benzyloxy-3-bromoindolines to afford an untapped family of isochromeno[3,4-b[indolines and 3-arylindoles, in which deformylative arylation of 2-(4-methoxybenzyloxy)-3-bromoindolines is reported for the first time. The isochromeno[3,4-b[indolines can be readily transformed into other heterocyclic moieties.

DOI： 10.1055/s-0039-1690734

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1002/hlca.201900116

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.3987/com-19-14077

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Authorship：Lead author,　Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society (ACS)  

DOI： 10.1021/acs.orglett.9b01108

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Authorship：Lead author,　Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society ({ACS})  

DOI： 10.1021/acs.orglett.8b04120

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Authorship：Lead author,　Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：Japan Institute of Heterocyclic Chemistry  

DOI： 10.3987/com-18-s(f)30

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Authorship：Last author,　Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：Royal Society of Chemistry ({RSC})  

<p>The regioselective synthesis of pyrano[3,2-<italic>e</italic>]indole alkaloid fontanesine B have been accomplished by C4 Pictet–Spengler cyclization and Bischler–Napieralski-type cyclization of a trichloromethyl carbamate.</p>

DOI： 10.1039/C9RA02321F

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society  

A novel cascade reaction of indole-2,3-epoxide equivalents with γ-carbolines by utilizing a double "open and shut" transformation to access multiheterocyclic compounds containing both isotryptamines and pyrimido[1,6-a]indoles has been developed. This strategy utilizes the in situ formation of a bulky quaternary ammonium salt via ammonium exchange, which undergoes Hofmann elimination/vinylogous Mannich/retro-Mannich/cyclization cascade sequences.

DOI： 10.1021/acs.orglett.8b00332

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society  

A concise synthesis of the azepinobisindole alkaloid iheyamine A from an indole-2,3-epoxide equivalent has been achieved. This method features a formal C3 electrophilic reaction of an indole-2,3-epoxide equivalent with tryptamine to form a 3-aminoindoline and a novel In-catalyzed dehydrative Mannich-type reaction of the hemiaminal to give the azepinobisindole core.

DOI： 10.1021/acs.orglett.8b00330

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Wiley Blackwell  

Phaitanthrin E was biomimetically synthesized from methyl indole-3-carboxylate and methyl anthranilate or anthranilic acid using the ester group as an activating group. The reaction proceeds through NCS-mediated dearomatization/TFA-catalyzed protonation of indolenine/C(2) amination/Et3N-promoted aromatization and cyclization in one-pot procedure. This method is capable of converting simple biomass materials to phaitanthrin E. The synthesis not only allows assessment of antiproliferative activity, but also affords experimental support for the hypothetical biosynthetic pathway of phaitanthrin E. The resulting phaitanthrin E derivatives were evaluated for in vitro antiproliferative activity against human colorectal cancer cells (DLD-1). The biogenetic intermediate of phaitanthrin E showed higher antiproliferative activity than the natural product, phaitanthrin E. Furthermore, a concise synthesis of tryptanthrin is also accomplished from indole-3-carbaldehyde and methyl anthranilate using the aldehyde group as an activating group.

DOI： 10.1002/hlca.201700284

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Authorship：Lead author,　Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Japan Institute of Heterocyclic Chemistry  

An acetyl chloride/NaI-mediated Nazarov-type cyclization of an indolyl vinyl ketone was developed to give a cyclopenta[b]indole in high yield. An acyl Finkelstein reaction is a key feature for this unprecedented Nazarov-type cyclization.

DOI： 10.3987/COM-18-13866

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Authorship：Lead author,　Last author,　Corresponding author   Language：Japanese   Publisher：The Society of Synthetic Organic Chemistry, Japan  

<p>We describe the total synthesis of indolo[2,1-b]quinazoline alkaloids tryptanthrin (1a), candidine (2), phaitanthrins A (3), B (4), C (5), cruciferane (8), and cephalanthrin A (9) using oxidative cascade sequences as the key step. Phaitanthrin E (7a) was synthesized by a novel methodology that features a concise approach involving the intermolecular condensation and intramolecular aryl C-H amination mediated by Cu-complexes to construct the indolo[2,1-b]quinazoline core. Moreover, an acid catalyzed one-pot synthesis of phaitanthrin E (7a) via intermolecular amination/intramolecular cyclization cascade using NCS was also developed.</p>

DOI： 10.5059/yukigoseikyokaishi.76.802

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Authorship：Lead author,　Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：Japan Institute of Heterocyclic Chemistry  

DOI： 10.3987/com-17-s(t)15

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

We have developed a self-relay copper(I)-catalyzed Ullmann N-arylation/2-amidation cascade to form functionalized indolo[1,2-a]quinazolinones in one-pot from easily available indoles with 2-bromobenzamides. This novel transformation features a tandem process of Ullmann-type coupling, activation of indolenine, and 2-amidation in the presence of a single copper catalyst. In addition, among the substituents of indoles at the C3 position, methyl carboxylate could act as an activating group in this Ullmann N-arylation/2-amidation cascade.

DOI： 10.1039/c7qo00549k

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：GEORG THIEME VERLAG KG  

The hyrtiazepine alkaloids are a family of bisindole natural products that have the azepinoindole backbone. We developed a biomimetic approach by constructing the azepinoindole core in a one-pot manner through 1,4-diazabicyclo[2.2.2]octane/2,2,2-trifluoroethanol (DABCO/TFE) promoted Pictet-Spengler reaction onto the C-4 position of tryptophan. This strategy allowed the synthesis of common key structures of these families. The key intermediate can be converted into the 3H-pyrano[2,3-b:5,6-e']diindol intermediate present in hyrtimomines A and B, as well as the azepinoindole core present in fargesine.

DOI： 10.1055/s-0036-1588438

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

A novel indole-2,3-epoxide equivalent, 2-hydroxyindbline-3-triethylammonium bromide, was found, to be a convenient reagent for formal C3-electrophilic reactions of indoles with various nudeophiles. By taking advantage of the nudeophilie character of the oxygen of the 2-hydroxyindo-line the interrupted retro-Claisen interrupted Feist - Benary reactions, with 1,3-dicarbonyl compounds Were efficiently achieved.

DOI： 10.1021/acs.orglett.7b01940

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

We have developed a copper-catalyzed Ritter-type reaction/cyclization cascade of anthranilic acids and nitriles, affording the quinazolin-4(3H)-ones. The cascade proceeds through a Ritter-type reaction capturing the iminoketene intermediates by nitriles. Furthermore, we found a novel Ritter-type reaction/condensation/intramolecular anti-Markovnikov hydroamination cascade, providing access to functionalized diazocines in one-pot.

DOI： 10.1039/c7cc01406f

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

The first syntheses of hyrtioreticulins C and D via a Pictet Spengler reaction at the C-4 position of the indole rings are described. The synthesis proceeds in only two steps from commercially available starting materials. In this Communication, the structures of the natural products were confirmed. Furthermore, we revise the signs of the specific rotations of hyrtioreticulins C and D.

DOI： 10.1021/acs.jnatprod.7b00008

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©2017 The Japan Institute of Heterocyclic Chemistry. We investigated the one-pot synthesis of several fused 2-pyridone ring systems based on a Curtius rearrangement, followed by a microwave-assisted thermal electrocyclization of a 2-aza-6?-electron system including isocyanate. We synthesized seven heterocyclic compounds containing a fused 2-pyridone ring. In these results, the one-pot synthesis of fused 2-pyridone ring system 5 from (E)-acrylic acids 1 under microwave irradiation conditions was more effective than the conventional reaction conditions in terms of the yield and the reaction time.

DOI： 10.3987/COM-16-S(S)13

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DOI： 10.3987/COM-16-S(S)5

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

We have developed a concise one-pot synthesis of phaitanthrin E derivatives, where simple starting materials undergo an acid-catalyzed intermolecular amination/intramolecular cyclization cascade.

DOI： 10.1021/acs.orglett.6b03466

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER FRANCE-EDITIONS SCIENTIFIQUES MEDICALES ELSEVIER  

We report a convenient synthesis of carbazole-1,4-quinone alkaloid koeniginequinones A and B using a tandem ring-closing metathesis with the dehydrogenation reaction sequence under an O-2 atmosphere as an important step. Using this method, carbazole-1,4-quinones substituted at the 5-, 6-, 7-, and/or 8-positions have been synthesized. Moreover, 24 compounds, including koeniginequinones A and B, have been evaluated for their antiproliferative activity against HCT-116 and HL-60 cells, and the 6-nitro analog exhibited the most potent activity against both tumor cell types. (C) 2016 Elsevier Masson SAS. All rights reserved.

DOI： 10.1016/j.ejmech.2016.05.065

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

A one-pot synthesis of phaitanthrin E starting from methyl indole-3-carboxylate and isatoic anhydride through intermolecular condensation/intramolecular aryl C-H amination cascade was developed.

DOI： 10.3987/COM-16-13465

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Other Link： http://orcid.org/0000-0003-1729-1097

Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

Concise syntheses of 9-methoxyellipticine, 3,4-dihydroellipticine (mu-alkaloid D), 1,2,3,4-tetrahydroellipticine, 2-methyl-1,2,3,4-tetrahydroellipticine, olivacine, 3,4-dihydroolivacine, (+/-)-guatambuine, and (+/-)-janetine were developed starting from hexatriene intermediates readily obtained by Pd-catalyzed tandem cyclization/cross-coupling reaction of indolylborates. The route enables the facile construction of pyrido[4,3-b]carbazoles by Cu-catalyzed 6 pi-electrocyclization and subsequent transformation of the pyridocarbazole intermediates into pyrido[4,3-b]carbazole alkaloids.

DOI： 10.1002/ejoc.201600246

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Total syntheses of koeniginequinones A and B, isolated from Murraya koenigii, were newly achieved by constructing of carbazole-1,4-quinone using a one-pot Pd-catalyzed cyclocarbonylation method with 2-(but-2-en-l-y1)-3-iodoindoles derived from known methyl 6-methoxyindole-2-carboxylate and methyl 5,6-dimethoxyindole-2-carboxylate, followed by desilylation, and an oxidation sequence.

DOI： 10.3987/COM-15-S(T)5

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Authorship：Lead author   Language：Japanese   Publisher：Society of Synthetic Organic Chemistry  

In our continuing study of the reactivity and synthetic application of indolylborate as a versatile synthetic intermediate, we found that the use of indolylborate in palladium-catalyzed cross -coupling reaction is highly effective for the synthesis of indole derivatives. The present account deals with the results concerning a novel approach to indole alkaloids based on the use of the palladium-catalyzed cross-coupling. Dimeric indole alkaloid, yuechuke, was synthesized through the palladium-catalyzed carbonylative cross-coupling reaction. Pyridocarbazole alkaloids (ellip-ticine, olivacine, and their related alkaloids), and indolophenanthridine alkaloid (calothrixins A and B) were obtained by the use of cyclization/cross-coupling domino reaction. In addition, (CuOTf) 2 toluene complex was demonstrated to catalyze 6π-electrocyclization of hexatrienes, leading to pyrido [4,3-b] carbazoles.

DOI： 10.5059/yukigoseikyokaishi.74.117

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

A one-pot conversion of skatole to tryptanthrin, an indolo[2,1-b]quinazoline alkaloid, was achieved by Cu-mediated oxidation.

DOI： 10.3987/COM-15-13228

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

The palladium-catalyzed intramolecular oxidative coupling reaction of 1,1'-carbonyldiindoles was achieved by using Pd(OAc)(2) and Cu(OAc)(2), producing 1,1'-carbonyl-2,2'-biindolyls, which were then converted to tjipanazoles D and I

DOI： 10.3987/COM-14-S(K)28

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Language：English   Publisher：ROYAL SOC CHEMISTRY  

This review covers the literature on simple indole alkaloids and those with a nonrearranged monoterpenoid unit from the beginning of 2012 up to the end of 2013, which includes newly isolated alkaloids, structure determinations, total syntheses and biological activities.

DOI： 10.1039/c5np00032g

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER BIRKHAUSER  

Calothrixin B, whose structure consists of a pentacyclic indolo[3,2-j] phenanthridine framework, was originally isolated as a secondary metabolite from Calothrix cyanobacteria and was found to exhibit potent antiproliferative activity. In this study, treatment with 100 mu M of calothrixin B did not inhibit the proliferation of HL-60 promyelocytic leukemia cells, the result indicated that calothrixin B could possess weaker activity against leukemia cells. In a previous study of the structure-antiproliferative activity relationships of calothrixin B analogs, the tetracyclic 5H-pyrido[4,3-b] carbazole-4,11(6H)-dione structure, which does not include the benzene ring found in calothrixin B, was reported to be necessary for antiproliferative activity; however, the induction of substituents on the indole nitrogen atom of calothrixin B decreased the antiproliferative activity of the compound. To develop calothrixin B analogs with good antiproliferative activity against both HL-60 and HCT-116 cells, we synthesized various N-substituted calothrixin B analogs and assessed their activity. Compared with calothrixin B, N-OMe calothrixin B displayed almost the same or slightly stronger antiproliferative activity against HCT-116 cells, whereas the N-MOM analog demonstrated slightly weaker activity against these cells. These two analogs also inhibited proliferation of HL-60 cells, whereas calothrixin B did not exhibit antiproliferative activity toward these cells. Among calothrixin B analogs, N-OMe and N-MOM calothrixins B are cytotoxic against HCT-116 cells and not the lack of the effect on HL-60 cells.

DOI： 10.1007/s00044-014-1061-6

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

A one-pot approach to indolo[2,1-b]quinazolines from indole-3-carbaldehydes through the Dakin oxidation was developed. It was shown that the reaction proceeded through the condensation of indole-3-carbaldehydes with isatoic anhydrides, derived in situ from indole-3-carbaldehydes by the Dakin oxidation, and further oxidation/cyclization steps. (C) 2014 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.tetlet.2014.07.113

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novel one-pot synthesis of carbazole-1,4-quinone by consecutive Pd-catalyzed cyclocarbonylation, desilylation, and oxidation reactions is described. We propose a possible mechanism of the cyclocarbonylation reaction between 3-iodo-2-propenylindole and CO (1 atm) in the presence of a tributyl(vinyl)tin and Pd-catalyst and the resulting acylpalladium species was directly coupled with a terminal alkene to produce the carbazole-1,4-quinone. To our knowledge, this is the first example of this type of reaction. A new formal total synthesis of a carbazole-1,4-quinone alkaloid, murrayaquinone A was established using this reaction. (C) 2014 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.tet.2014.01.015

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A one-pot synthesis of 3,3'-bisindolylmethanes was developed through the intermolecular Pummerer reaction using indole as a nucleophile.

DOI： 10.3987/COM-13-S(S)31

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9,10-Phenanthrenequinone (9,10-PQ) is one of the most abundant quinones among diesel exhaust particulates. Recent data have suggested that quinones induce apoptosis in immune, epithelial and tumor cells, leading to respirator illness; however, the mechanisms by which quinones induce apoptosis and the structure required for this remain unknown. We studied the antitumor activity of 9,10-PQ analogs against two human tumor cell lines, HCT-116 colon tumor cells and HL-60 promyelocytic leukemia cells. The loss of the cis-orthoquinone unit in 9,10-PQ abrogated its ability to induce apoptosis in the two tumor cell lines, and the LC50 values of these analogs were indicated over 10 mu M. An analog of 9,10-PQ in which the biaryl unit had been deleted displayed a reduced ability to induce tumor cell apoptosis, while the analogs 1,10-phenanthroline-5,6-dione (9) and pyrene-4,5-dione (10), which also had modified biaryl units, exhibited increased tumor cell apoptotic activity. The cis-orthoquinone unit in 9,10-PQ was identified as essential for its ability to induce apoptosis in tumor cells, and its biaryl unit is also considered to influence orthoquinone-mediated apoptotic activity. (C) 2013 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.bmcl.2013.06.015

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The development of biomimetic reactions is one of the major challenges for synthetic chemists, because mimicking these complicated reactions in the laboratory by simple catalytic systems is difficult to achieve in general. Vitamine B6-dependent aminotransferase-catalyzed transamination of α-keto acids from pyridoxamine is an important process to generate α-amino acids in nature. In this review, recent progresses on the biomimetic transamination of α-keto esters are described.

DOI： 10.5059/yukigoseikyokaishi.71.62

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A one-pot approach to 3,3′-bisindolylmethane derivatives from nitrobenzene derivatives through the Bartoli indole synthesis was developed, in which the acid used to quench the reaction markedly affected its outcome. Quenching the reaction with concd HCl produced 3,3′-bisindolylmethane in contrast to the formation of 7-substituted indole by quenching with NH 4Cl. © 2013 American Chemical Society.

DOI： 10.1021/ol401486s

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This review describes a synthesis of indole compounds using multifunctional synthons. The multifunctional synthons, trienes and gramines, were respectively synthesized using Pd-catalyzed tandem cyclization/cross-coupling reaction of indolylborate with vinyl bromide, and reaction of indolylcuprate with iminium chloride. As an application of the multifunctional synthons to the indole alkaloids synthesis, we accomplished the total synthesis of ellipticine, 9-methoxyellipticine, 9-hydroxyellipticine, tetrahydroellipticine, μ-alkaloid B, μ-alkaloid D, calothrixin A, calothrixin B, tubifoline, and yuehchukene. We have also developed 6π-electrocyclization of hexatrienes catalyzed by Cu(I) trifluoromethanesulfonate toluene complexe, which is unprecedented. © 2013 The Pharmaceutical Society of Japan.

DOI： 10.1248/yakushi.12-00233

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This review covers the literature on simple indole alkaloids and those with a non-rearranged monoterpenoid unit from the beginning of 2010 up to the end of 2011, which includes newly isolated alkaloids, structure determinations, total syntheses and biological activities.

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A short total synthesis of a bisindole alkaloid, yuechukene, was achieved through the dimerization of beta-dehydroprenylindole generated in situ from 1-(indol-3-yl)-3-methylbut-2-en-1-amine.

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The palladium-catalyzed tandem cyclization/cross-coupling reaction of triethyl(indol-2-yl)borate with vinyl bromide was successfully used in the concise total synthesis of the indolophenanthridine alkaloids, calothrixins A and B.

DOI： 10.1002/ejoc.201200657

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We synthesized calothrixin B using our developed biomimetic method and derived N-alkyl-calothrixins A and B. The in vitro antimalarial activity of the calothrixin derivatives, including calothrixins A and B, against the Plasmodium falciparum FCR-3 strain was evaluated. All test compounds exhibited antimalarial activity over a concentration range of 6.4 x 10(-6)-1.2 x 10(-7) M. (C) 2012 Elsevier Ltd. All rights reserved.

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The concise total synthesis of calothrixins A and B has been accomplished by utilizing the one-pot formation of hexatriene as a key intermediate via the palladium-catalyzed tandem cyclization/cross-coupling reaction of triethyl(indo1-2-yl)borate. In another key transformation, the indolo[3,2-j]phenanthridine core was prepared in high yield via Cu(I)-mediated 6 pi-electrocyclization.

DOI： 10.1021/ol201107a

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A novel and simple protocol for the synthesis of 1-(2-aminoethyl)pyrano[3,2-e]indole derivatives has been developed using the Pictet-Spengler reaction of N-b-benzylserotonin with alpha,beta-unsaturated aldehydes in the presence of Et3N in 2-propanol or MeOH.

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Cu- and Rh-catalyzed coupling reactions of 2-azabicyclo[2.2.1]hept-5-en-3-ones (1) with arylboronic acids were successful carried out under microwave irradiation conditions and yielded N-aryl and C-aryl derivatives of 1, respectively.

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This review covers the literature on simple indole alkaloids and those with a nonrearranged monoterpenoid unit, and includes newly isolated alkaloids, structure determinations, total syntheses and biological activities.

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It was shown that dichloramine-T (1) reacted with cyclohexene in acetonitrile to give N&apos;-(2-chlorocyclohexyl) amidine 2a and N-(2-chlorocyclohexyl)acetamide (3) via the competitive addition of acetonitrile and N-chloro-N-tosylamino anion to cyclohexenechloronium ion. This reaction can be catalyzed by Cu(OAc)(2), primarily affording 2a. Furthermore, the resulting 2a can be cyclized to benzimidazol 14a in good yield by treating with KOH in dioxane.

DOI： 10.1002/hlca.200900214

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Quorum sensing (QS) systems have been discovered in a wide variety of bacteria, and mediate both intra- and interspecies communication. The AI-2-based QS system represents the most studied of these proposed interspecies systems and has been shown to regulate diverse functions such as bioluminescence, expression of virulence factors, and biofilm formation. As such, the development of modulatory compounds, both agonists and antagonists, is of great interest for the study of unknown AI-2-based QS systems and the potential treatment of bacterial infections. The fimbrolide class of natural products has exhibited excellent inhibitory activity against AI-2-based QS and as such may be considered the "gold standard" of AI-2 inhibitors. Thus, we sought to include a fimbrolide as a control compound for our recently developed alkyl-DPD panel of AI-2 modulators. Herein, we present a revised synthesis of a commonly studied fimbrolide as well as a direct comparison between the fimbrolide and alkyl-DPD analogues. We demonstrate that our alkyl-DPD analogues are more potent inhibitors of QS in both Vibrio harveyi and Salmonella typhimurium, the two organisms with defined AI-2 QS systems, and in doing so call into question the widely accepted use of fimbrolide-derived compounds as the "gold standard" of AI-2 inhibition.

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The reaction of N-beta-benzylserotonin with alpha,beta-unsaturated and aryl aldehydes in the presence of a base produced 1H-azepino[5,4,3-cd]indoles.

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Rhodium-catalyzed arylation of 2-azabicyclo[2.2.1]hept-5-en-3-one was successfully performed by applying microwave irradiation.

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The palladium-catalyzed tandem cyclization-cross-coupling protocol using 1H-indol-2-yltrialkylborate (indolylborate) proved to be a versatile approach to the generation of 2-(4-piperidylmethyl)indole, which was successfully used for the preparation of (+/-)-tubifoline.

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Copper-catalyzed N-arylation reaction of 2-azabicyclo[2.2.1]hept-5-en-3-one (ABH) with arylboronic acids was successively performed in the presence of KOH and trimethylamine-N-oxide under microwave irradiation. © The Japan Institute of Heterocyclic Chemistry.

DOI： 10.3987/COM-07-S(N)6

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Palladium-catalyzed tandem cyclization - cross-coupling reaction of indolylborate 2 and vinyl bromide 5 was successfully applied in a short formal synthesis of olivacine. The reaction of 2 with 5 in the presence of Pd(OAc)(2) readily afforded three kinds of products, triene derivative 6 and vinylindole derivative 7, along with a small amount of the piperidine derivative 8 (Scheme 2). On the other hand, the reactions of 2 with bromide 10 or 15 were also examined (Schemes 4 and 5) and their outcome markedly depended oil the relative ease of ring closure as a function of ring size. Irradiation of 6 with a high-pressure pressure mercury lamp (-9; Scheme 2), followed by removal of the N-[(benzyloxy)carbonyl] group and subsequent oxidation afforded, after deprotection, pyridocarbazole 23, and the conversion of 23 to olivacine is known (Scheme 6).

DOI： 10.1002/hlca.200890195

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Catalytic asymmetric syntheses of (-)-centrolobine and (-)-de-O-methylcentrolobine have been achieved, incorporating a hetero-Diels-Alder (HDA) reaction between 4-aryl-2-silyloxy-1,3-butadienes and phenylpropargyl aldehyde derivatives as a key step. The HDA reaction using dirhodium(II) tetrakis[(R)-3-(benzene-fused-phthalimido)-2-piperidinonate], Rh-2(R-BPTPI)(4), as a chiral Lewis acid catalyst provides exclusively cis-2,6-disubstituted tetrahydropyran-4-ones in up to 93% ee. (C) 2007 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.tet.2007.09.003

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[GRAPHICS]
Dirhodium(II) tetrakis[N-tetrafluorophthaloyl-(S)-tert-leucinate], Rh-2(S-FPTTL)(4), is an exceptionally efficient catalyst for enantioselective aminations of silyl enol ethers derived from acyclic ketones or a,beta-enones with [N-(2-nitrophenyisulfonyl)imino]phenyliodinane (NsN=IPh), providing N-(2-nitrophenyisulfonyl)-alpha-amino ketones in high yields and with enantioselectivities of up to 95% ee. The effectiveness of the present catalytic protocol has been demonstrated by an asymmetric formal synthesis of (-)-metazocine.

DOI： 10.1021/o1702019b

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The enantioselective aziridination of alkenes with [N-(4-nitrophenylsulfonyl)imino]phenyliodinane catalyzed by dirhodium(II) tetrakis[N-tetrachlorophthaloyl-(S)-tert-leucinate], Rh-2(S-TCPTTL)(4), is described. While such enantioselectivities are highly dependent on the properties of the alkenes, 2,2-dimethylchromene was found to be a particularly suitable substrate which can be efficiently transformed into the aziridine product in 98% yield with 94% ee.

DOI： 10.3987/COM-07-S(K)63

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The first successful example of the enantioselective intermolecular 1,3-dipolar cycloaddition of a chiral dirhodium(II) catalyst-associated carbonyl ylide with an aromatic aldehyde dipolarophile is described. The tandem carbonyl ylide formation/cycloaddition reactions of 1-diazo-5-aryl-2,5-pentanediones with aromatic aldehydes using dirbodium(II) tetrakis[N-benzene-fused-phthaloyl-(S)-valinate] as a catalyst provide exclusively exo cycloadducts in up to 92% ee.

DOI： 10.1002/adsc.200600591

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Regioselectivity on the reaction of (1-methylindol-2-yl)cyanocuprate with N-(prop-2-en-1-ylidene)aminium chlorides was investigated.

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An efficient and reliable procedure for the preparation of dirhodium(II) tetrakis[N-phthaloyl-(S)-tert-leucinate], Rh-2(S-PTTL)(4), a universally effective catalyst for a range of enantioselective carbene transformations, is described. The N-phthaloylation of (S)-tert-leucine by the method of Bose with essentially no racemization is a key to this process.

DOI： 10.1248/cpb.53.1366

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Language：Japanese   Publisher：公益社団法人 有機合成化学協会  

DOI： 10.5059/yukigoseikyokaishi.78.637

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DOI： 10.5059/yukigoseikyokaishi.76.851

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DOI： 10.24496/tennenyuki.60.0_583-588

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Clavicipitic acid (1), aurantioclavine (2), fargesine (3), cimitrypazepine (4),
hyrtiazepine (5), hyerimomine A-C (6-8), hyrtinadines C, D (9, 10) and hyrtioleticulins C, D
(11, 12) are a unique family of indole alkaloids characterized by a novel
azepino[5,4,3-cd]indole ring system. In our continuing interest in the synthesis of indole
alkaloids, we have developed a biomimetic approach by constructing the
azepino[5,4,3-cd]indole in a one-pot manner through the base promoted C-4 Pictet-Spengler reaction of Nb-benzylserotonin (13) or 5-hydroxytryptophan methyl ester (19) with aldehydes. This strategy allowed the synthesis of common key structures of azepinoindole
families.
A concise synthesis of aurantioclavine (5) was accomplished in only three steps from
Nb-benzylserotonin (13) and aldehyde 20 by using this strategy. The reaction of 13 with 20
in the presence of Et₃N in MeOH, followed by treatment with Tf₂O provided azepinoindole 29 in 60% yield. Subsquentry, conversion of 29 to 2 was achived via catalytic reduction.
Recentry, we reported the first synthesis of the azepinoindole alkaloid hyrtioreticulins
C and D (11, 12) through a C-4 Pictet-Spengler reaction between 5-hydroxytryptophan
methyl ester (19) and acetaldehyde (21). The C-4 Pictet-Spengler reaction using DIEA in
MeOH was carried out under microwave irradiation, and allowed to give trans-25a and
cis-25b in 59% and 4% yield, respectively. The methyl esters 25 were subjected to
hydrolysis and gave hyrtioreticulins C and D (11, 12) in 70-72% yield.
On the other hand, the reaction of 19 with indole-3-carbaldehyde 22 was successful in
the presence of DABCO in TFE, leading to 26 in 85% yield. The removal of Ts and Bn
group were performed by Mg/MeOH and H₂/Pd-C provided 32 in 50%. Further
transformation to 5 was failed due to instability of 32 under oxidation conditions.
Further studies directed to the synthesis of other azepinoindole alkaloids with the use of
base-promoted C-4 Pictet-Spengler reaction are in progress.

DOI： 10.24496/tennenyuki.59.0_405

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<p> Tryptanthrin (1a), a indolo[2,1-b]quinazoline alkaloid with a potent antitumor activity, was isolated from the culture of fungus Candida lipolytica. Several related alkaloids, such as candidine (2), phaitanthrins A (3), B (4), C (5), D (6), E (7), cruciferane (8), and cephalanthrin A (9) have also been found in a wide range of natural sources. Because their diverse biological activities and structural intricacy, these alkaloids have been the target numerous synthetic studies. We envisaged oxidative dimerization of indoles for the construction of these indolo[2,1-b]quinazoline. Herein, we describe the total synthesis of indolo[2,1-b]quinazoline alkaloids tryptanthrin (1a), candidine (2), phaitanthrins A (3), B (4), C (5), E (7), cruciferane (8), and cephalanthrin A (9) using oxidative dimerization of indoles or amination/condensateion cascade as the key step.</p><p> After intensive investigations, we found that urea hydrogen peroxide (UHP) prompted dimerization of indole-3-carbaldehyde (10a) to tryptanthrin (1a) in good yields, while other oxidants did not cause this dimerization at all. In addition, oxidative dimerization of skatole (11a) via C-H oxidation, afforded 1a, could proceed in the presence of CuI and PCC. </p><p> Next, the conversion of 1a to phaitanthrins A (3), B (4), C (5) cruciferane (8), and cephalanthrin A (9) could be carried out. In the course of their synthesis, the unprecedented one-pot formation of candidine (2) via trimerization of 10a in the presence of UHP and a catalytic amount of (PhSe)₂ was also observed. </p><p> Phaitanthrin E (7) was also synthesized by a novel methodology that features a concise approach involving the intermolecular condensation and intramolecular aryl C-H amination mediated by Cu-complexes to construct the indolo[2,1-b]quinazoline core. In the key Cu-mediated condensation/amination cascade, a combination of CuI and Et₃N turned out to effect conversion of methyl indole-3-carboxylate (15) to phaitanthrin E (7) in one-pot protocol. Moreover, the acid catalyzed one-pot synthesis of phaitanthrin E (7) via intermolecular aryl C-H amination/intramoecular cyclization cascade using NCS was also developed. </p>

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9,10-Phenanthrenequinone (9,10-PQ) is one of the most abundant quinones among diesel exhaust particulates. Recent data have suggested that quinones induce apoptosis in immune, epithelial and tumor cells, leading to respirator illness; however, the mechanisms by which quinones induce apoptosis and the structure required for this remain unknown. We studied the antitumor activity of 9,10-PQ analogs against two human tumor cell lines, HCT-116 colon tumor cells and HL-60 promyelocytic leukemia cells. The loss of the cis-orthoquinone unit in 9,10-PQ abrogated its ability to induce apoptosis in the two tumor cell lines, and the LC50 values of these analogs were indicated over 10 μM. An analog of 9,10-PQ in which the biaryl unit had been deleted displayed a reduced ability to induce tumor cell apoptosis, while the analogs 1,10-phenanthroline-5,6-dione (9) and pyrene-4,5-dione (10), which also had modified biaryl units, exhibited increased tumor cell apoptotic activity. The cis-orthoquinone unit in 9,10-PQ was identified as essential for its ability to induce apoptosis in tumor cells, and its biaryl unit is also considered to influence orthoquinone-mediated apoptotic activity.9,10-Phenanthrenequinone (9,10-PQ) is one of the most abundant quinones among diesel exhaust particulates. Recent data have suggested that quinones induce apoptosis in immune, epithelial and tumor cells, leading to respirator illness; however, the mechanisms by which quinones induce apoptosis and the structure required for this remain unknown. We studied the antitumor activity of 9,10-PQ analogs against two human tumor cell lines, HCT-116 colon tumor cells and HL-60 promyelocytic leukemia cells. The loss of the cis-orthoquinone unit in 9,10-PQ abrogated its ability to induce apoptosis in the two tumor cell lines, and the LC50 values of these analogs were indicated over 10 μM. An analog of 9,10-PQ in which the biaryl unit had been deleted displayed a reduced ability to induce tumor cell apoptosis, while the analogs 1,10-phenanthroline-5,6-dione (9) and pyrene-4,5-dione (10), which also had modified biaryl units, exhibited increased tumor cell apoptotic activity. The cis-orthoquinone unit in 9,10-PQ was identified as essential for its ability to induce apoptosis in tumor cells, and its biaryl unit is also considered to influence orthoquinone-mediated apoptotic activity.

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A one-pot approach to 3,3'-bisindolylmethane derivatives from nitrobenzene derivatives through the Bartoli indole synthesis was developed, in which the acid used to quench the reaction markedly affected its outcome. Quenching the reaction with concd HCl produced 3,3'-bisindolylmethane in contrast to the formation of 7-substituted indole by quenching with NH4Cl.A one-pot approach to 3,3'-bisindolylmethane derivatives from nitrobenzene derivatives through the Bartoli indole synthesis was developed, in which the acid used to quench the reaction markedly affected its outcome. Quenching the reaction with concd HCl produced 3,3'-bisindolylmethane in contrast to the formation of 7-substituted indole by quenching with NH4Cl.

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Covering: 2010-2011. Previous review: Nat. Prod. Rep. 2010, 27, 1630-1680This review covers the literature on simple indole alkaloids and those with a non-rearranged monoterpenoid unit from the beginning of 2010 up to the end of 2011, which includes newly isolated alkaloids, structure determinations, total syntheses and biological activities.Covering: 2010-2011. Previous review: Nat. Prod. Rep. 2010, 27, 1630-1680This review covers the literature on simple indole alkaloids and those with a non-rearranged monoterpenoid unit from the beginning of 2010 up to the end of 2011, which includes newly isolated alkaloids, structure determinations, total syntheses and biological activities.

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<p> Ellipticine (1), a pyridocarbazole alkaloid with a potent antitumor activity, was isolated from Ochrosia elliptica Labill in 1959. Due to its unique structure as well as potent antitumor activity, 1 have attracted much attention in chemical and biological communities. The structurally-related alkaloids calothrixin A (2) and B (3), a potent antitumor antibiotics, were isolated from cyanobacteria Calothrixin 1999. These alkaloids are characterized by the fused polycyclic ring systems including carbazole. Although there have been reported 6p-electrocyclization that allow concise construction of carbazole core, there was no precedent for construction of carbazoles by catalytic 6p-electrocyclization. We envisaged catalytic 6p-electrocyclization of triene containing indole for the construction of these carbazole core. Herein, we describe the total synthesis of antitumor indole alkaloids based on the Pd-catalyzed tandem cross-coupling/cyclization and Cu-catalyzed 6p-electrocyclization of trienes. </p><p> The triene 6 were readily synthesized from indolylborate 4 and enyne 5 by Pd-catalyzed tandem cross-coupling/cyclization in one-pot protocol. After intensive investigations, we found that (CuOTf)₂•toluene complexes prompted cyclization of 6 to carbazole 7 in good yields, while other Lewis acids and metal complexes did not cause this cyclization at all. In addition, this Cu-promoted cyclization could proceed in the presence of catalytic amount of (CuOTf)₂•toluene complexes. This is a first example for 6p-electrocyclization catalyzed by Cu-complexes. Finally, deprotection and oxidation sequeneces of 7 gave ellipticine (1), 9-methoxyellipticine (10), m-alkaloid D (12) and tetrahydroellipticine (13). In the almost same manner, we have completed total synthesis of olivacine (20), guatambuine (22) and janetine (23) as well from carbazole 7d.</p><p> Calothrixin A (2) and B (3) were also synthesized by a convergent methodology that features a concise approach involving the above-mantioned Pd-catalyzed tandem cross-coupling/cyclization, Cu-catalyzed 6p-electrocyclization to construct the carbazole core and Dakin oxidation. In the key Cu-catalyzed 6p-electrocyclization and Dakin oxidation, a combination of Cu(OAc)₂ and PCC turned out to effect conversion of 6b to 26 in one-pot protocol. </p>

DOI： 10.24496/tennenyuki.56.0_Poster4

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Language：Japanese  

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Language：Japanese   Publisher：Division of Organic Chemistry, The Pharmaceutical Society of Japan  

We have demonstrated a new approach to synthesizing calothrixins A and B through the palladium-catalyzed tandem cyclization/cross-coupling reaction of indolylborate by taking advantage of the one-pot generation of the hexatrienes as a key intermediate for constructing indolophenanthridine. In addition, the unprecedented use of CuOTf for 6&pi;-electrocyclization of hexatriene was developed. In another key transformation, indolophenanthridine quinone core of calothrixins was prepared from the indolophenanthridine aldehyde <I>via</I> one-pot Dakin oxidation sequence catalyzed by diphenyldiselenide.

DOI： 10.14895/hannou.37.0.18.0

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Language：Japanese   Publisher：Division of Organic Chemistry, The Pharmaceutical Society of Japan  

Aryl-substituted 2-azabicyclo[2.2.1]heptanes (aryl-ABH) have significant biological activities. To open the concise entry to aryl-ABH, we have examined metal-catalyzed cross-coupling reaction of arylboronic acids and ABH. When the reaction was carried out with arylboronic acid and ABH in the presence of rhodium/copper combined catalyst under microwave irradiation, diarylated ABH were obtained in one-pot manner. Rhodium complex promoted catalytic addition of arylboronic acids to the double bonds of ABH, and copper complex were essential for the catalytic N-arylation of the amide moiety of ABH.

DOI： 10.14895/hannou.36.0.8.0

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Language：Japanese   Publisher：Division of Organic Chemistry, The Pharmaceutical Society of Japan  

Pictet-Spengler reaction is one of the most versatile synthetic method in heterocyclic synthesis. Generally, tryptamine derivatives are known to react with aldehydes under acidic or neutral conditions to produce beta-calbolines. On the other hand, we have found that the reaction of Nb-benzylserotonin with aldehydes in the presence of a base proceeded the cyclization to the 4-position of the indole ring, producing azepino[5,4,3-cd]indoles. Therefore, we have investigated the applicability of other aldehydes and serotonin derivatives to the cyclization reaction to devise a novel synthetic route to azepinoindole alkaloids.

DOI： 10.14895/hannou.35.0.55.0

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Language：Japanese   Publisher：Division of Organic Chemistry, The Pharmaceutical Society of Japan  

The 1,2-differentiated diamination of unactivated alkenes was achieved using dichloramine-T (TsNCl₂ and CH₃CN as nitrogen sources in the presence of a catalytic amount of copper(II) complex. Various alkenes and nitriles could be applicable for the diamination, in which the cis-selectivities were observed in all cases. However, a few substrates gave poor yields mainly due to the formation of haloamine side product which would arised from ring-opening of the aziridinium intermediates by Cl^- in an S_N2 manner instead of CH₃CN. In these cases, the enhanced formation of diamine was observed when the reaction was performed at -20 C. The methodology described herein allows rapid access to cis-vicinal diamines.

DOI： 10.14895/hannou.34.0.8.0

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Language：Japanese   Publisher：Division of Organic Chemistry, The Pharmaceutical Society of Japan  

The arylation of 2-azabicyclo[2.2.1]hept-5-en-3-ones (ABH) with arylboronic acids was achieved using a catalytic amount of a rhodium(I) complex under microwave irradiation, in which the ring-opening of ABH and the multiple alkylation did not occur. The remote substituents effects on the chemical yields and the regioselectivities (syn : anti = 56 : 44 to 85 : 15) were observed. On the other hand, the reaction under the conventional conditions was sluggish in all cases. Using copper(II) complex, addition of arylboronic acids to N-H ABH under the conventional conditions afforded N-arylated ABH in good yield. In this case, the microwave irradiation was also found to promote the arylation of ABH, improving the rates and yields of these reactions.

DOI： 10.14895/hannou.33.0.54.0

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A recent study from our laboratory has shown that Rh₂(S-TCPTTL)₄, characterized by substitution of chlorine atoms for four hydrogen atoms on the phthalimido group in the parent Rh(II) complex, is well suited for enantioselective C&ndash;H amidation reation with [(4-nitrophenyl)sulfonylimino]phenyliodinane. As a logical extension of our study in this area, we addressed the enantioselective amidation of silyl enol ethers catalyzed by chiral Rh(II) carboxylates. The Rh(II)-catalyzed aziridination of acyclic silyl enol ethers with [(2-nitrophenyl)sulfonylimino]phenyliodinane followed by treatment with aq. TFA afforded optically active &alpha;-amino ketones. The fluorinated catalyst, Rh₂(S-TFPTTL)₄, proved to be the catalyst of choice for this process, exhibiting the highest enantioselectivity of 95% ee. The effectiveness of the present catalytic method has been demonstrated by the enantioselective synthesis of (&ndash;)-metazocine.

DOI： 10.14895/hannou.32.0.28.0

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