Determination of the Absolute Configuration of a Secondary Hydroxy Group in a Chiral Secondary Alcohol Using Glycosidation Shifts in Carbon-13 Nuclear Magnetic Resonance Spectroscopy

Abstract

A new method is proposed for determining the absolute configuration of a secondary hydroxy group in a chiral secondary alcohol using glycosidation shifts in 13C NMR spectroscopy. The 13C FT NMR spectra of a number of secondary alcoholic glucopyranosides in pyridine-d5 were compared with those of methyl glucosides and the corresponding parent alcohols to obtain the glucosidation shifts; Δδs = δ (alcoholic glucoside) - δ(methyl glucoside) for sugar moieties and Δδa = δ(alcoholic glucoside) - δ(alcohol) for aglycone moieties. Characteristic Δδs(C-1'), Δδa(C-α), and Δδa(C-β) values were obtained for the various kinds of secondary alcohols. They are summarized as a few rules for determining the absolute configuration of the hydroxyl. © 1978, American Chemical Society. All rights reserved.