An NMR Method for Assigning Relative Stereochemistry to β-Hydroxy Ketones Deriving from Aldol Reactions of Methyl Ketones

Abstract

We describe a simple ¹H NMR analysis that permits the stereochemistry of β-hydroxy ketones to be assigned by visual inspection of the ABX patterns for the α-methylene unit of the β-hydroxy ketone in the ¹H NMR spectra. This method has been verified by application to a wide range of β-hydroxy ketones deriving from aldol reactions of chiral aldehydes with a variety of chiral and achiral methyl ketone enolates (see Tables 1 and 2). The stereochemistry of 54 of these compounds have been assigned by rigorous chemical methods.