Theoretical Study on the Two-State Reaction Mechanism for the Formation of a Pyridin-2-one Cobalt Complex from Cobaltacyclopentadiene and Isocyanate

Rhodium-catalyzed asymmetric synthesis of silicon-stereogenic silicon-bridged arylpyridinones

A rhodium-catalyzed regio- and enantioselective synthesis of silicon-stereogenic silicon-bridged arylpyridinones was developed. A reasonable catalytic cycle was also experimentally established.

A rhodium-catalyzed regio- and enantioselective synthesis of silicon-stereogenic silicon-bridged arylpyridinones has been developed through [2 + 2 + 2] cycloaddition of silicon-containing prochiral triynes with isocyanates. High yields and enantioselectivities have been achieved by employing an axially chiral monophosphine ligand, and this process could be applied to catalytic asymmetric synthesis of silicon-stereogenic chiral polymers for the first time. The reaction mechanism of the present catalysis has also been experimentally investigated to establish a reasonable catalytic cycle, advancing the mechanistic understanding of the rhodium-catalyzed pyridinone synthesis by [2 + 2 + 2] cycloaddition reactions.

A terminal, fluxional η4-benzene complex with a thermally accessible triplet state is the primary photoproduct in the intercyclobutadiene haptotropism of (CpCo)phenylenes

Low-temperature irradiation of linear [3]- and [4]phenylene cyclopentadienylcobalt complexes generates labile, fluxional η(4)-arene complexes, in which the metal resides on the terminal ring. Warming induces a haptotropic shift to the neighboring cyclobutadiene rings, followed by the previously reported intercyclobutadiene migration. NMR scrutiny of the primary photoproduct reveals a thermally accessible 16-electron cobalt η(2)-triplet species, which, according to DFT computations, is responsible for the rapid symmetrization of the molecules along their long axes. Calculations indicate that the entire haptotropic manifold along the phenylene frame is governed by dual-state reactivity of alternating 18-electron singlets and 16-electron triplets.