Nitroso derivatives of l,3-dithiol-2-ylidenes, and related systems

Abstract

A range of substituted l,3-dithiol-2-ylidene systems have been prepared. These species have, subsequently, been converted to nitroso derivatives. The role of the 4-, 5- and ylidene subtituents in stabilising the nitroso-alkene moiety thus obtained has been investigated. X-ray molecular crystal data which show that these species are stabilised by intramolecular interactions are presented. Conversion of the nitroso derivatives to their thionitroso analogues has been attempted, but was unsuccessful. A selection of l-(l,3-dithiol-2-ylidene)-prop-2-ene systems have been prepared. These systems have been shown to be sufficiently activated to undergo nitrosation reactions at the 3-vinyl positon, though the nitroso-alkenes thus formed are unstable. A new route to 4,5-dicarbomethoxy-2-(tributylphosphino)-l,3-diselenolium tetrafluoroborate utilising hydrogen selenide as the source of selenium has been detailed. This Wittig reagent has been employed in the synthesis of various 1,3-diselenol-ylidene systems. Conversion to nitroso derivatives has been accomplised and X-ray data shows that the resultant nitroso-alkenes are stabilised by an intramolecular oxygen—selenium interaction.