One pot oxidative dehydration - oxidation of polyhydroxyhexanal oxime to polyhydroxy oxohexanenitrile: A versatile methodology for the facile access of azasugar alkaloids

Abstract

A unique oxidative dehydration-oxidation of polyhydroxy-oxime (7) to the corresponding ketonitrile (8) in one pot is reported for the first time in carbohydrate literature. Key ketonitrile intermediate (8) upon palladium hydroxide mediated cascade reaction afforded 1-deoxynojirimycin (DNJ) 1b in moderate diastereoselectivity. The cascade reaction involves the conversion of nitrile to amine, heteroannulation, reduction of the imine and subsequent debenzylation to furnish the azasugars. This oxidative dehydration-oxidation and reductive heteroannulation methodology is successfully utilized for the total synthesis of 1-deoxynojirimycin (1b), miglitol (2) and miglustat (3).

Keywords: Alcohol oxidation & oxime dehydration; Cascade reaction; Deoxynojirimycin; Miglitol; Miglustat; Reductive aminative cyclization.