Stereochemical studies of the palladium-catalyzed rearrangements of chiral 2-alkynyl sulfinates into chiral allenyl sulfones

Palladium-catalyzed reactions of diastereomerically pure chiral 2-alkynyl p-toluenesulfinates under very mild reaction conditions gave both enantiomers of optically active sulfonyl allenes in good yields with high stereospecificity. The stereochemistry of this transformation with the assistance of a palladium catalyst was determined. The conversion rate was measured by the HPLC analysis in accordance with the elapse of the reaction time, and the rather marked difference of the rate was observed between the diastereomeric sulfinates. A novel mechanism for this transformation with palladium catalysts is proposed.