Formation of α‐Hydroxy‐β‐diketones through Hydroxylation of Isoxazolium Salts: Stereoselective Approach to Angular cis‐Diols in Polycyclic Systems

Only two steps were needed for the unprecedented oxidation of isoxazoles, which is exploited in the stereocontrolled introduction of an “angular cis-diol” characteristic of polyketide-derived polycyclic natural products, such as 3. In this two-step process, 1) N-methylation of isoxazole 1 and 2) stereoselective epoxidation of isoxazolium salt 2 with sodium hypochlorite followed by hydrolysis are carried out (Bn: benzyl).