YANAGIYA Yuki Teikyo University, Faculty of Pharmaceutical Sciences, Research Associate, 薬学部, 助手 (10200544)
HONDA Takeshi Teikyo University, Faculty of Pharmaceutical Sciences, Research Associate, 薬学部, 助手 (60173663)
|Budget Amount *help
¥2,000,000 (Direct Cost : ¥2,000,000)
Fiscal Year 1992 : ¥500,000 (Direct Cost : ¥500,000)
Fiscal Year 1991 : ¥1,500,000 (Direct Cost : ¥1,500,000)
An increase in the biological significance of saccharide moieties of carbohydrate-containing biomolecules has generated considerable interest in the rational design and implementation of stereocontrolled glycosidation reactions. Our efforts in this area have led to the development of new glycosyl donors incorporating diphenyl phosphate, diphenylphosphinimidate, or phosphorodiamidimidothioate as leaving groups, the glycosidations of which constitute mild and efficient methods for the highly stereocontrolled construction of 1,2-trans-beta- and 1,2-cis-alpha-glycosidic linkages. After an extensive evaluation of substituents on the phosphorus atom of the leaving groups, we have now found that glycosyl donors incorporating N,N,N',N'-tetramethyl-phosphoroamidates exhibit not only excellent shelf-stabilities but also the following distinct advantages in the glycosidation reactions.
TMSOTf-promoted glycosidation of the benzyl-protected glycopyranosyl N,N,N',N'-tetramethyl-phosphoroamidates exhibits the highest 1,2-trans-beta-selectivity known to date. The phosphoroamidates can be also activated by boron trifluoride etherate to result in the predominant formation of 1,2-trans-beta-linked steroidal glycosides. Apart from the glycosidation without neighboring group participation, glycosidation of benzoyl-protected glycopyranosyl phosphoroamidates led to the exclusive formation of 1,2-trans-beta-linked glycosides or disaccharides with the aid of TMSOTf or boron trifluoride etherate as promoters. As an extension of the above results, stereocontrolled syntheses of 2-deoxy-alpha or beta-glycosides and 2-amino-2-deoxy-beta-glycosides have been achieved