An efficient synthesis of stable sulfur-containing phosphoranes derived from 2-mercapto-1-methylimidazole and 2-thiazoline-2-thiol

Abstract

Stable crystalline phosphorus ylides were obtained in excellent yields from the 1:1:1 addition reaction between triphenylphosphine and dialkyl acetylenedicarboxylates in the presence of strong SH-acids, such as 2-mercapto-1-methylimidazole and 2-thiazoline-2-thiol. These stable ylides exist in solution as a mixture of two geometrical isomers as a result of restricted rotation around the carbon–carbon partial double bond resulting from conjugation of the ylide moiety with the adjacent carbonyl group.

Keywords:

• Stable phosphorus ylide
• Acetylenic esters
• 2-Mercapto-1-methylimidazole and 2-Thiazoline-2-thiol
• Triphenylphosphine
• Geometrical isomers

Acknowledgements

We gratefully acknowledge financial support from the Research Council of the University of Sistan and Balouchestan.