Dibenzothiepin Derivatives and Related Compounds. IV. Reactions of Various Cyclic Ketones including 6, 11-Dihydrodibenzo-[b, e] thiepin-11-ones with SbCl₅

Abstract

In order to examine the reaction of 6, 11-dihydrodibenzo [b, e] thiepin-11-ones (21) and antimony pentachloride, reaction of various ketones with SbCl₅ or HCl-SbCl₅ was carried out. Tricyclic ketones (1a-d) gave the corresponding protonation products (9a-d) but monocyclic ketones, such as diphenylcyclopropenone (13) and γ-pyrone (19) only formed ketone-SbCl₅ adducts (1 : 1) (12, 18) with SbCl₅ and protonation products (14, 20) with HCl-SbCl₅. Stereochemical considerations were made on the formation mechanism of these products. Reaction of 6, 11-dihydrodibenzo [b, e] thiepin-11-one (21) with SbCl₅ gave the anticipated protonation product (22) but that of 6-chloro-6, 11-dihydrodibenzo [b, e] thiepin-11-one (5) and SbCl₅ resulted in cleavage of the thiepin ring, contrary to expectations, and a compound (23) of undetermined structure was obtained. This compound (23) transited to bis [2-(2-formylbenzoyl) phenyl] disulfide (24) by hydrolysis.