Synthesis and nitrosation reactions of π-extended 1,3-dithiol-2-ylidene systems

Abstract

New 1,3-dithiol-2-ylidene derivatives, notably π-extended systems, have been synthesised by Wittig reactions of phosphorane and phosphonate ester derivatives of 1,3-dithiole with activated ketones and α,β-unsaturated ketones. Nitrosation reactions of a range of these π-extended systems, results in the formation of nitroalkenes, via unstable nitrosoalkene intermediates, which, in general, could not be isolated. The X-ray crystal structure of 1-(4,5-dicarbomethoxy-1,3-dithiol-2-ylidene)-1-cyano-1-phenyl-methane reveals a small degree of intramolecular electron transfer from the dithiole ring to the conjugated cyano group.