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([double bond, length half m-dash]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.

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