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DOI: 10.1039/A806396F (Paper) Reference Section for: J. Chem. Soc., Perkin Trans. 1, 1998, 3731-3736

X-Ray crystallographic analysis and photochemical reaction of asymmetrically substituted α,β-unsaturated thioamides

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Masami Sakamoto, Masaki Takahashi, Kenji Kamiya, Wataru Arai, Kentaro Yamaguchi, Takashi Mino, Shoji Watanabe and Tsutomu Fujita

Abstract

Photochemical reaction of asymmetrically substituted N-benzyl-N-isopropyl-α,β-unsaturated thioamides both in solution and in the solid state was investigated. All thioamides exist in an equilibrium between two rotamers owing to the rotation of the C([double bond, length half m-dash]S)–N bond. The free energy of activation for the bond rotation was estimated by temperature-dependent 1H NMR spectroscopy. The free energy of activation lies in a range 18.4–19.5 kcal mol–1. Irradiation in benzene solution proceeded to give hydrogen abstraction by alkenyl carbon from both benzyl and isopropyl groups, leading to β-thiolactam and 1,3,5-dithiazinane products, respectively. Hydrogen abstraction from only the isopropyl group took place in the solid-state photolysis, giving an isomeric β-thiolactam product.

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