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.

本研究报道了一种环境友好型合成方法，可在室温、温和条件的水相体系中，通过丙酮与Oxone®原位生成二甲基二氧杂环丙烷（dimethyldioxirane），实现丙二酸酯及其环状类似物的α-羟基化反应。该方法具有底物依赖性，可成功应用于α-羟基化γ-内酯的制备。为验证该温和α-羟基化反应的合成应用潜力，本研究开发了两条不同的简洁合成路线，以外消旋形式合成哈里亚内酯A，产物的非对映异构体比例为适中的3:1。