X-Ray crystallographic analysis and the photochemical reaction of N-benzyl-N-methylmethacrylthioamide in solution and the solid state

Abstract

Photochemical reaction of asymmetrically substituted N-benzyl-N-methylmethacrylthioamide both in solution and in the solid state was investigated. The thioamide exists in an equilibrium between two rotamers owing to rotation about the C(S)–N bond. The free energy of activation for the bond rotation was estimated as 22.7 kcal mol–1 by temperature-dependent 1H NMR spectroscopy. The thioamide crystallized in a chiral fashion, and the photoreaction in the solid state gave the optically active β-thiolactam whereas both the β-thiolactam and the corresponding thiazolidinethione were obtained by solution-phase photochemistry.