A Facile Synthesis of Stable Phosphorus Ylides Derived from Harmin, Harman, and Carbazole

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 NH-acids, such as harman, harmin, and carbazole. These stable ylides exist in solution as a mixture of two geometrical isomers as a result of the restricted rotation around the carbon–carbon partial double bond resulting from the conjugation of the ylide moiety with the adjacent carbonyl group.

Keywords:

• Acetylenic ester
• NH ─ acids
• stable phosphorus ylides
• triphenylphosphine