Studies on the deactivation mechanism of the reaction of N,N-dialkylamides with TMDS catalyzed by Vaska's complex, IrCl(CO)(PPh 3 ) 2 (1a), triggered the discovery of highly active Ir-PPh 3 catalysts: Photochemically activated 1a and thermally activated IrCl(PPh 3 ) 3 (8). Both catalysts showed excellent activity toward the selective conversion of a variety of N,N-dialkyl-, N-alkyl-N-aryl-, and N,N-diarylamides to the corresponding enamines with low catalyst loadings. The 14-electron species "ClIr(PPh 3 ) 2 ", which is stabilized by solvents or reactants in the actual catalytic reactions, could be involved in the catalysis, which produces "HIr(PPh 3 ) 2 " and "SiIr(PPh 3 ) 2 " (Si = Me 2 HSiOMe 2 Siâ') species in the catalytic cycle. An in situ generation method for the "ClIrL 2 " species was established by simply mixing [IrCl(Î• 4 -COD)] 2 with PPh 3 or other phosphorus ligands, which realized the facile large-scale syntheses of enamines.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Organic Chemistry
- Inorganic Chemistry