Details

Autor(en) / Beteiligte

• Li, Zhi-Feng
• Li, Hui-Xue
• Yang, Xiao-Ping
• Liu, Xin-Wen
• Zuo, Guo-Fang
• Zhao, Cunyuan

Titel

Direct coupling of unactivated alkynes and C(sp3)-H bonds catalyzed by a Pt(ii, iv)-centered catalyst: a computational studyElectronic supplementary information (ESI) available: The complete citation for ref. 37, the Cartesian coordinates for the calculated stationary structures at calculated levels are given. See DOI: 10.1039/c5ra05458c

Erscheinungsjahr

2015-04

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Direct coupling of unactivated alkynes and C(sp 3 )-H bonds catalyzed by a Pt( ii , iv )-centered catalyst X (X = PtCl 2 , PtBr 2 , PtI 2 and PtI 4 ) ( J. Am. Chem. Soc. 2009, 131 , 16525) have been theoretically investigated with density functional theory (DFT). A comprehensive mechanistic DFT study of these reactions was carried out to better understand the experimental outcomes, and divergent and substrate-/catalyst-dependent mechanisms for the formation of ether derivatives were uncovered based on the computational results. Free energy diagrams for three types of mechanisms were computed, (a) in Mechanism I, the transition state implies a directed 1,5-hydrogen shift (pathways a1-a4 ), (b) Mechanism II leads to the formation of a Pt( ii , iv ) vinyl carbenoid (pathway b ), and (c) Mechanism III involves an O-coordinated Pt and includes 5,6-hydrogen migration (pathway c ). Results suggest that the catalytic mechanism with PtI 4 is different to PtCl 2 , PtBr 2 and PtI 2 catalysts. When PtCl 2 , PtBr 2 and PtI 2 were used the insertion reaction pathway a2 is favored while PtI 4 adopted the pathway a1 . Comparing the energy profiles, the pathway a1 with PtI 4 is the most favored. Through 1,5-hydrogen transfer, the concerted insertion pathway a1 with carbocationic intermediate is favored while the vinyl carbenoid mechanism is implausible. Direct coupling of unactivated alkynes and C(sp 3 )-H bonds catalyzed by a Pt( ii , iv )-centered catalyst X (X = PtCl 2 , PtBr 2 , PtI 2 and PtI 4 ) ( J. Am. Chem. Soc. 2009, 131 , 16525) have been theoretically investigated with density functional theory (DFT).