Faculty Profiles - SAWADA Daisuke

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A new and facile synthesis of carbamate- and urea-linked glycoconjugate using modified Curtius rearrangement Reviewed

Daisuke Sawada, Shinya Sasayama, Hideyo Takahashi, Shiro Ikegami

TETRAHEDRON LETTERS 47 ( 40 ) 7219 - 7223 2006.10

Language：English Publisher：PERGAMON-ELSEVIER SCIENCE LTD

We describe a facile synthetic method of carbamate- and urea-linked glycoconjugates using sugar carboxylic acids by the modified Curtius rearrangement. This reaction is a simple one-pot procedure, and various nucleophiles including tertiary alcohols can be utilized to afford desired compounds in moderate to high yields. And the stereospecific synthesis of the anomeric isomers is achieved using the corresponding two stereoisomers of glycosyl carboxylic acid. (c) 2006 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.tetlet.2006.07.139

Divergent synthesis of (L)-sugars and (L)-iminosugars from D-sugars Reviewed

Hideyo Takahashi, Tomomi Shida, Yuko Hitomi, Yoshinori Iwai, Namisa Miyama, Kazusa Nishiyama, Daisuke Sawada, Shiro Ikegami

CHEMISTRY-A EUROPEAN JOURNAL 12 ( 22 ) 5868 - 5877 2006.7

Language：English Publisher：WILEY-V C H VERLAG GMBH

An efficient divergent synthesis Of L-sugars and L-iminosugars from D-sugars is described. The important intermediate, delta-hydroxyalkoxamate, prepared from D-glucono-/galactono-1,5-lactone, was cyclized under Mitsunobu conditions to give the O-cyclized oxime compound and the N-cyclized lactam compound as mixtures. A more detailed investigation revealed that the appropriate protecting groups and solvents controlled the specificity for the O-/N-cyclization of the delta-hydroxyalkoxamate. Suitable protection at the delta-position of 6-hydroxyalkoxamate, derived from D-glucono-1,5-lactone, afforded the corresponding delta-alkylation product alone. Thus we succeeded in applying this to the total synthesis of L-iduronic acid. In contrast, with both TBDMS as the protecting group and RCN as the solvent the efficient conversion of D-glucono/galactono-1,5-lactone into the corresponding L-iminosugars (L-idonolactam and L-altronolactam) was achieved.

DOI： 10.1002/chem.200600268

Highly enantioselective cyanosilylation of aldehydes catalyzed by a Lewis acid-Lewis base bifunctional catalyst Reviewed

Yoshitaka Hamashima, Daisuke Sawada, Hiroyuki Nogami, Motomu Kanai, Masakatsu Shibasaki

Tetrahedron 57 ( 5 ) 805 - 814 2001.1

A new bifunctional asymmetric catalyst containing a Lewis acid and a Lewis base (1) was developed and applied to the catalytic asymmetric cyanosilylation of aldehydes. The products were obtained generally with excellent enantiomeric excess. The experiments using the control catalyst (5) and the catalyst containing more electron-rich phosphine oxide (6) suggest that the catalyst 1 should promote the reaction via a dual activation of the aldehyde by the aluminum and TMSCN by the phosphine oxide. This reaction is practical and was applied to the catalytic asymmetric total synthesis of epothilone A. © 2001 Elsevier Science Ltd.

DOI： 10.1016/S0040-4020(00)01039-5

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