The Reaction of Thioimides with Phosphorus Ylides

Article abstract of DOI:10.1021/jo00017a017

The reaction of a series of thioimides with phosphorus ylides, in a manner analogous to the Wittig reaction, has been examined.The resulting reaction products represent potentially valuable intermediates in tetrapyrrole pigment synthesis.In addition to the desired thio-Wittig-type coupling reaction, the presence of two competing reaction pathways, S-alkylation and oxidation/reduction, has been observed with certain substrates.These empirical observations have been correlated to theoretical data, derived from MNDO and ab initio calculations, which delineate the structu re-reactivity relationships governing product distribution from the various reaction pathways.A detailed analysis is presented of the mechanism of the thio-Wittig coupling reaction and the competitive S-alkylation reaction.