Ring Opening of<i>C</i>-Glycosides under Mild Conditions

Abstract

C-glycosides 2, 4, 7 and 12 react with dimethylboron bromide to form the acyclic alkenes 5, 6, 8 and 13 respectively. In this reaction, the ether linkage of the tetrahydropyran ring is opened without cleavage of the acetoxy groups. Alkene 13 (E,4R,5S,6R)-4,5,6,7-tetraacetoxy-2-heptenoic acid) is an important intermediate in the synthesis of KDO (3-deoxy-D-manno-2-octulosonic acid).