The base-catalysed rearrangement of α-acetolactate (2-hydroxy-2-methyl-3-oxobutanoate) : a novel carboxylate ion migration in a tertiary ketol rearrangement

Abstract

The base-catalysed racemisation of α-acetolactic acid (2-hydroxy-2-methyl-3-oxobutanoic acid)(1) has been shown to proceed by reversible tertiary ketol rearrangement with migration of the carboxylate ion rather than the methyl group. The intramolecular nature of the rearrangement was demonstrated by examination, using ¹³C n.m.r., of the rearrangement of [1, 3-¹³C₂]-2-hydroxy-2-methyl-3-oxobutanoate (18).