DFT Studies on the Mechanism of the Iridium-Catalyzed Formal [4 + 1] Cycloaddition of Biphenylene with Alkenes

Recently, we reported an Ir-catalyzed formal [4 + 1] cycloaddition of biphenylenes with alkenes, which gave 9,9-disubstituted fluorenes in moderate to excellent yields. We proposed a reaction mechanism that involved the intermolecular insertion of alkenes, β-elimination, and intramolecular insertion based on the results of experimental mechanistic studies. Herein, we further support the proposed mechanism by density functional theory calculations and explain why [4 + 1] cycloaddition proceeds rather than conventional [4 + 2] cycloaddition

Pt-Catalyzed Enantioselective Cycloisomerization for the Synthesis of Planar-Chiral Ferrocene Derivatives

Enantioselective cycloisomerization of 2-ethynyl-1-ferrocenylbenzene derivatives proceeded by using a chiral cationic platinum catalyst at room temperature. The intramolecular reaction gave planar–chiral naphthalene- and anthracene-fused ferrocene derivatives with high to excellent ee

Ir-Catalyzed Synthesis of Substituted Tribenzosilepins by Dehydrogenative C–H/Si–H Coupling

The Ir-catalyzed intramolecular reaction of 2′,6′-diaryl-2-(hydrosilyl)­biphenyls gave substituted tribenzosilepins by direct dehydrogenative C–H/Si–H coupling. This is the first example of catalytic construction of the tribenzosilepin skeleton. Enantiomerically pure tribenzosilepin was prepared by optical resolution using chiral HPLC, and its inversion barrier was calculated by measurement of rate of racemization using the Eyring kinetic equation under heating conditions