Vijaya N. Desai

Stereocontrolled 1,3-addition reaction of silyl ketene acetal to sugar nitrone: synthesis of d-gluco-homo-1-deoxynojirimycin and l-ido-homo-1-deoxynojirimycin

Abstract The 1,3-addition reaction of silyl ketene acetal 6 to d -glucose derived nitrone 7 followed by reductive cleavage of the N–O bond afforded d -gluco- and l -ido-β-amino ester derivatives of 9a and 9b. The diastereoselectivity in addition reaction was improved as well as altered by making use of different Lewis acids. Reduction of the ester group in 9a followed by hydrogenolysis gave amino alcohol 12a. Selective N-Cbz protection, hydrolysis and intramolecular reductive amination afforded d -gluco-homo-1-deoxynojirimycin 1d. Analogously, β-amino ester 9b was converted to l -ido-homo-1-deoxynojirimycin 1c.

A NEW ROUTE TO AMINOSUGARS FROM SUGAR NITRONES : SYNTHESIS OF 6-DEOXYNOJIRIMYCIN

Abstract The 1,3-addition of methylmagnesium chloride to dialdose derived nitrones 3 and 7 afforded N- benzylhydroxylamines 4 5 and 8 9 , respectively, in high yields. The stereoselectivity of the addition reaction was improved by the use of trimethylsilyl triflate. The NO bond reductive cleavages of N-benzylhydroxylamines took place in good yields and offered an easy access to N-benzylaminosugars. The potential of these aminosugars is demonstrated by the synthesis of glycosidase inhibitor 6-deoxynojirimycin 1a.

Intramolecular Michael addition of benzylamine to sugar derived α,β-unsaturated ester: a new diastereoselective synthesis of a higher homologue of 1-deoxy-L-ido-nojirimycin

The diastereoselective intramolecular Michael addition of the benzylamine generated in situ from hemiacetal 3 leads to the lactone 4a with the required homoazasugar ring skeleton; reduction of the lactone functionality and removal of the protecting groups afford 1-deoxy-L-ido-homonojirimycin.

An unusual observation in the rhodium carbenoids: [1,4]-migration in the sugar-derived α-diazo-β-ketoesters

In competition with [1,2]-migration, [2,3]-sigmatropic rearrangement and C–H insertion, product formation via an unusual [1,4]-migration is also found to be a prominent process in the rhodium carbenoids derived from sugar α-diazo-β-keto esters 2a–d.