Dehydrative glycosidations of 2-deoxysugar derivatives catalyzed by an arylboronic ester.

An N-methylpyridinium-4-boronic ester acts as a catalyst for dehydrative glycosidations of 2-deoxy sugar-derived hemiacetals. The catalytic protocol is tolerant of functionalized acceptors, including alcohols bearing isopropylidene ketal, tert-butyl carbamate or benzyl carbamate groups. The results demonstrate that organoboron-catalyzed substitution reactions of alcohols, which have previously been conducted on π-activated (benzylic, allylic or propargylic) substrates, can also be used to achieve C-O bond formation from carbohydrate-derived hemiacetals.