A Convergent Strategy for the Synthesis of β-Carba-galacto-disaccharides

A convergent strategy for the synthesis of β-carba-galacto-disaccharides is illustrated by the preparation of 1 and 4, from a central “glycone” component 22, and the corresponding “aglycone” segments, monosaccharide alcohols, 23a or 23b. The key step is the formation of the carbasugar ring via an oxocarbenium ion−enol ether cyclization