Oxone®-Mediated Direct α-Hydroxylation of β-Dicarbonyl Compounds: Racemic Synthesis of Harzialactone A

An environmentally benign method is described for the α-hydroxylation of malonates and cyclic analogues in aqueous medium at room temperature under mild conditions, based on the in situ generation of dimethyldioxirane through the combination of acetone and Oxone®. This procedure was found to be substrate-dependent and was successfully performed to provide α-hydroxylated γ-lactones. To demonstrate the synthetic potential of this mild α-hydroxylation, two different concise routes were developed to synthesize harzialactone A in the racemic form with a moderate (3:1) diastereomeric ratio.