Photoisomerization of 2H, 6H??thiin??3??one 1??oxides to 3H, 7H??[1, 2] oxathiepin??4??ones

R Kowalewski, P Margaretha

Index: Kowalewski, Ronald; Margaretha, Paul Helvetica Chimica Acta, 1993 , vol. 76, # 3 p. 1251 - 1257

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Citation Number: 10

Abstract

Abstract Oxidation of 2H, 6H-thiin-3-ones 1a–c with 3-chloroperbenzoic acid affords the corresponding 1-oxides 2a–c. On irradiation (350 nm) in either benzene or MeCN, these cyclic sulfoxides 2 isomerize to 3H, 7H-1, 2-oxathiepin-4-ones 3. The tetramethyl derivative 3a is isolated by flash chromatography at− 10, but, at higher temperatures, it undergoes ring contraction and H 2 O elimination to give 4, 4-dimethyl-2 (2-methylprop-2enylidene) ...