Functionalized 1-anilinoazetidin-2-ones by photochemical ring contraction of pyrazolidinones

Abstract

2-Phenylpyrazolidin-3-ones substituted in the 4-position by a side chain containing hydroxy, amino, or acetamido functional groups undergo photochemical ring contraction to the corresponding 1-anilino-azetidin-2-ones. Retention of stereochemistry during the rearrangement was demonstrated by X-ray crystallographic analysis for the hydroxy-substituted pyrazolidinone.