Synthetic Exploration of α‐Diazo γ‐Butyrolactams

DIazo transfer reaction onto γ‐butyrolactams (activated by α‐ethyloxalylation) gave rare α‐diazo γ‐butyrolactams. Decomposition of the latter by Rh 2 (OAc) 4 in the presence of alcohols and water gave products of O–H insertion of the respective metal‐cabene species. Silver triflate (1 mol‐%) was found to convert the γ‐butyrolactams investigated into 1,5‐dihydro‐2 H ‐pyrrol‐2‐ones which represent versatile building blocks. Particular instability was noted for α‐diazo γ‐butyrolactams bearing alkyl or o ‐substituted aryl substituents on the nitrogen atom. These were found to dimerize in solution or upon storage at room temperature to give fully conjugated bis‐hydrazones along with the loss of a nitrogen molecule.