Acylketene [4+2] cycloadditions: divergent de novo synthesis of 2,6-dideoxy sugars

Abstract

The synthetic methodology demonstrated herein provides a divergent, de novo synthetic pathway to 2,6-dideoxy carbohydrates. Pyranone 2, which was prepared by [4+2] cycloaddition of the acylketene generated from dioxinone 1 with butyl vinyl ether, was converted in a straightforward manner to arabino-hexopyranosides olivoside 11 and oleandroside 12, and branched sugars olivomycoside 14 and chromoside B 15, with near complete control of relative stereochemistry at the three newly introduced stereogenic centers. Olivoside 11 proved to be a pivotal intermediate for elaboration to the ribo, lyxo, and xylo families of 2,6-dideoxy carbohydrates