Photochemical reactions of 2‐bornanethione (thiocamphor) with bis(methylthio)ethyne. Addition and intramolecular hydrogen abstraction

Abstract

Abstract Irradiation of a mixture of bornanethione 7 and bis(methylthio)ethyne 2a afforded a mixture of methyl E ‐ and Z ‐2‐(2‐bornylidene)‐2‐(methylthio)ethanedithioate 8 and E ‐1,2‐bis‐(methylthio)vinyl 2‐bornen‐2‐yl sulfide 10 E . The first compounds are the products of the (2 + 2)‐photocycloaddition reaction between bornanethione 7 and acetylene 2a . The sulfide 10 E is rationalised as being the product of an intramolecular H abstraction reaction of the 1,4‐biradical 12 which is also believed to be the intermediate in the (2 + 2)‐cycloaddition reaction.