Conformation of C‐1‐Substituted Pyranos‐1‐yl and Pyranosan‐5‐yl Radicals Evidence for a Quasi‐Homo‐Anomeric Stabilization Effect

Abstract

Acetylated 1‐cyano‐ and 1‐chloro‐pyranos‐1‐yl radicals and 5‐acetoxycarbonyl‐, 5‐methoxycarbonyl‐, and 5‐unsubstituted pyranosan‐5‐yl radicals were generated from the corresponding bromides by bromine abstraction with trimethyltin radicals. The conformation of these radicals, as deduced from the ESR hyperfine splittings, is explained by the combined action of a quasi‐anomeric and a homo‐anomeric stabilization effect. A captodative substitution pattern of the radical center does not influence the conformations.