Photochemical reactions of N-acyldithiocarbamates and N-acylthiocarbamates

Abstract

Photochemical hydrogen abstraction from N-acyltetrahydro- 1,3-thiazine-2-thiones, N-acyloxazolidine-2-thiones and N-acyltetrahydro-1,3-oxazine-2-thiones have been studied. Irradiation of N-(diphenylacetyl)-and N-(alkoxyacetyl)tetrahydro-1,3-thiazine-2-thiones in benzene at 40°C gave bicyclic lactams, 5,7-dithia-1-azabicyclo[4.3.0]nonan-9-ones, accompanied by Norrish Type-II cleavage products, whereas N-acetyl and N-isobutyryl derivatives gave only cleavage products. Photolysis of N-(diphenylacetyl)-, N-(methoxyacetyl)-and N-(ethoxyacetyl)-tetrahydro-1,3-thiazine-2-thiones at 0 °C followed by acetylation afforded cepham analogues, 6-acetylthio-5-thia-lazabicyclo[4.2.0]octan-8-ones. N-Acyloxazolidine-2-thiones underwent Norrish Type-II cleavage to give oxazolidine-2-thione and the corresponding esters (O-acylmethanols) as the sole products on irradiation in methanol. N-Acetyl- or N-isobutyryltetrahydro-1,3-oxazine-2-thiones underwent only Norrish Type-II cleavage whereas N-(alkoxyacetyl)tetrahydro-1,3-thiazine-2-thiones underwent cleavage and also gave 5-oxa-7-thia-1 -azabicyclo[4.3.0]nonan-9-ones.