A computational mechanistic study of Pd(II)-catalyzed gamma-C(sp(3))-H olefination/cyclization of amines: the roles of bicarbonate and ligand effect

作者：Liu, Jian-Biao^*; Tian, Ying-Ying; Zhang, Xin; Wang, Lu-Lin; Chen, De-Zhan^*

来源：Dalton Transactions, 2018, 47(14): 4893-4901.

DOI：10.1039/c8dt00015h

• C-H FUNCTIONALIZATION
• CARBON-HYDROGEN BONDS
• C(SP(3))-H BONDS
• DIRECTING-GROUP
• SELECTIVE ALKENYLATION
• ALIPHATIC-AMINES
• DIRECT ARYLATION
• EN-ROUTE
• PALLADIUM
• OLEFINATION

The detailed mechanism of palladium-catalyzed -C(sp(3))-H olefination/cyclization of triflyl-protected amines was investigated by density functional theory (DFT) calculations. The olefinated intermediate was initially formed in the first catalytic cycle involving ligand exchange, bicarbonate-assisted C(sp(3))-H bond cleavage, alkene insertion and reductive -hydride elimination'. The following syn-addition and reductive elimination furnish the aza-Wacker product. The first step of reductive elimination is the rate-determining step. The mechanism unveils the important roles of bicarbonate: aiding the C-H activation and abstracting the -proton in the second step of reductive elimination. The parallel bridging mode in the metal-olefin intermediate facilitates the syn-addition, explaining the experimentally observed stereoselectivity. The effect of the monodentate pyridine-based ligands is also discussed.

• 出版日期2018-4-14
• 单位山东师范大学