Endocyclic cleavage of glycosides. VI. Substituent effects of the alkylative endocyclic cleavage of glycosides

A number of pentopyranoside derivatives were treated with Me ₃ Al in order to investigate the influence of structural parameters on the methyl group transfer in the endocyclic alkylative cleavage reaction of these substrates. A cyclic CH ··· O hydrogen bonded model is suggested as an intermediate, which is used to explain the stereoselectivities for different substrates. In several, cases the diastereoselectivities were better than 9:1.