PMR spectra and conformation of some four‐membered rings containing one nitrogen atom. 2‐Azetidinones, 2‐azetidinethiones and 1‐azetines

Abstract

Abstract By PMR studies at different temperatures a planar conformation is proposed for the 2‐azetidinone, 2‐azetidinethione and 1‐azetine rings. The chemical shifts and the vicinal and geminal coupling constants of the ring methylene protons are reported and discussed. The application of the relationship between the J gem value and the angle between the methylene group and the adjacent 7r‐bond is considered.