Divergent syntheses of all 16 carbasugar stereoisomers via stereoconversion of carba-beta-D-altropyranose derivatives

Abstract

We have developed practical synthetic routes to enantiopure D- and L-carba-beta-altrose derivatives and all the possible stereoisomers via their divergent stereoconversions. Carba-beta-D-altrose was prepared from 3-cyclohexene-l-carboxylic acid and converted to carba-beta-D-mannose, carba-beta-D-idose, and carba-beta-D-talose derivatives via regio- and stereoselective oxidation/reduction of 3-OH and/or 4-OH. The four carbasugar stereoisomers were then transformed to the remaining 12 carbasugar stereoisomers and their 1,2-epoxides by regio- and stereoselective manipulation of hydroxyl groups in C1 and C2, which includes oxidation/reduction, Mitsunobu's reaction, olefination/dihydroxylation, and epoxidation/ring-opening protocols. (c) 2005 Elsevier Ltd. All rights reserved.