Stereochemistry of sapelin B; correlation with sapelin D. Anomalies in the use of shift reagents for determining the absolute configurations of α-glycols

Abstract

The c.d. spectrum of sapelin B tribenzoate (7) and correlation with sapelin D (1) have shown sapelin B (6) to be 23R,24S, in agreement with their origin from a common biogenetic precursor; the c.d. spectra of sapelin B and methyl 4,6-O-ethylidene-α-D-glucopyranoside in the presence of Pr(dpm)₃ exhibit Cotton effects of opposite signs to those predicted.