872415-82-2Relevant academic research and scientific papers
Cleavage of carbonyl carbon and α-carbon bond of acetophenones by iridium(III) porphyrin complexes
Li, Bao Zhu,Song, Xu,Fung, Hong Sang,Chan, Kin Shing
, p. 2001 - 2003 (2010)
Selective carbonyl carbon (C( - O)) and α-carbon (C(methyl)) bond activation of acetophenones was discovered by the high-valent, iridium(III) 5,10,15,20-tetrakis-4-tolylporphyrinato carbonyl chloride (Ir(ttp)Cl(CO)), which also acted as a Lewis acid in catalyzing the aldol condensation of acetophenones together with release of the coproduct water. Preliminary mechanistic studies suggest that both aliphatic and aromatic carbon-hydrogen bond activation products are kinetic products, which can be converted by reaction with water to iridium porphyrin hydride (Ir(ttp)H) via iridium porphyrin hydroxide (Ir(ttp)OH). Both Ir(ttp)OH and Ir(ttp)H were the possible intermediates to cleave the C( - O)-C(methyl) bond of acetophenones and to generate iridium porphyrin acyl complexes as the thermodynamic products.
Scope and mechanism of carbonyl carbon and α-carbon bond cleavage of ketones by Iridium(III) porphyrin complexes
Li, Bao Zhu,Fung, Hong Sang,Song, Xu,Chan, Kin Shing
, p. 1984 - 1990 (2011/05/06)
Chemoselective carbonyl carbon and α-carbon bond activation (CCA) of ketones (RCOR) was successfully achieved with various iridium(III) tetrakis-4-tolylporphyrinato complexes Ir(ttp)X (X = (BF4)(CO), Cl(CO), and Me) to give the corresponding Ir(ttp)COR (R = Ar, Me, or Et) and Ir(ttp)R (R = Me or Et) complexes. Ir(ttp)(BF4)(CO) exhibited the highest reactivity toward CCA, as it possesses a higher Lewis acidity in catalyzing the aldol condensation of ketones to give water, which hydrolyzes the kinetic products, C-H bond activation (CHA) complexes, into the proposed Ir(ttp)OH for a subsequent CCA process. The CCA step is nonregioselective in giving both Ir(ttp)R and Ir(ttp)COR. However, Ir(ttp)R was kinetically less stable toward hydrolysis to give Ir(ttp)OH. Thus, only Ir(ttp)COR was observed as the sole CCA product.
