A facile synthesis of diastereoisomeric stable 1,4-diionic and also phosphorus ylides compounds contaning sulfur through the reaction between 1,3-dicarbonyl compounds with activated acetylenic esters

The addition of triphenylphosphine to dialkyl acetylenedicarboxylates in the presence of 1,3-diethyl-2-thiobarbituric acid, cyclohexanone-2-carboxylate or 2-acetylcyclopentanone led to highly functionalized 1,4-diionic organophosphorus compounds and also stable phosphorus ylides respectively. These thio betaines possess two vicinal stereogenic centers and exist as a mixture of two diastereoisomers. The stable phosphorus ylides also 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.