BASE-CATALYZED REARRANGEMENT OF ALPHA-ACETOLACTATE "(2-HYDROXY-2-METHYL-3-OXOBUTANOATE) - NOVEL CARBOXYLATE ION MIGRATION IN A TERTIARY KETOL REARRANGEMENT

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).