Convenient syntheses of deoxypyranose sugars from glucuronolactone

One of the characteristic reactions of glucuronic acid derivatives is the base-catalysed elimination of a 4-(substituted) hydroxy group to generate a Δ4,5 pyranose. Following hydrogenation, proceeding mainly from the α-face provided the anomeric configuration is β, the initial C(5)-configuration is restored. This sequence affords access to a number of 4-deoxypyranoses: thus 4-deoxyglucoses are readily available by reduction at C(6). Conversion to a glycal, then cis-dihydroxylation at C(2)/C(3) leads to the d-lyxo configuration (found in neosidomycin). Finally a less obvious relationship to the KDO series is revealed, again by dihydroxylation.