Oxyfunctionalization of ketones bearing α‐methylene group with piperidine oxoammonium salt. Synthesis of α‐diketones from monoketones

A facile method for the title transformation is described. The reaction of 2,2,6,6‐tetramethyl‐4‐methoxypiperidine oxoammonium chloride (1b) and ketones bearing α‐methylene group in acetonitrile proceeded smoothly to give the α‐oxyfunctionalized coupling products (6a‐h). These coupling products decomposed upon heating in acidic medium to produce α‐diketones (7a‐h) in good to excellent yields.