Photochemical transformations of small ring heterocyclic compounds. 91. Photochemistry of the chroman and 3-chromanone ring systems. An example of tautomeric control of excited-state chemistry
Uncatalyzed conjugate addition of organozinc halides to enones in DME: a combined experimental/computational study on the role of the solvent and the reaction mechanism
calculations, prompted by the experimental aggregation study, revealed an unexpected reactionmechanism, where the coordinating capabilities of DME stabilize a transition state involving two organozinc moieties, lowering the activation energy of the reaction with respect to that seen for THF, enough to explain the fast and quantitative reactions observed experimentally and the different behaviors of
Conjugate Addition of Organoboron Compounds to α,β-Unsaturated Ketones Catalyzed by Nickelacycles
作者:Kazuhiko Semba、Yoshiaki Nakao、Kotaro Nagase
DOI:10.1055/a-2150-2912
日期:2023.11
catalytic activity of nickelacycles in the conjugate addition of arylboronates to α,β-unsaturatedketones was investigated. Nickelacycles afforded β-arylated ketones in moderate to high yields, whereas an analogous palladacycle did not catalyze the reaction. Studies on the time course of the reaction confirmed that the nickelacycles act as active species in the conjugate addition reaction.
Wide bite angle diphosphine rhodium complexes: Synthesis, structure, and catalytic 1,4-addition of arylboronic acids to enones
作者:Brad P. Morgan、Rhett C. Smith
DOI:10.1016/j.jorganchem.2007.09.034
日期:2008.1
A rhodium complex [ClRh(CO)(L1)] featuring a wide bite angle diphosphine ligand (L1 = 1,3-bis(2-diphenylphosphinomethylphenyl)benzene) has been synthesized and structurally characterized. L1 supports a bite angle (P-M-P angle, beta) of 171.4 degrees in the trans-square planar complex. L1 was tested in Rh-catalyzed 1,4-addition reactions of arylboronic acids (six examples) to alpha,beta-unsaturated ketones (five examples). In mixed aqueous/cyclohexane solution at 60 degrees C, addition reactions proceed in up to quantitative yield with a 1: 1 arylboronic acid/enone ratio. Yields as high as 77% can be acquired even when one of the coupling partners is sterically encumbered 2,4,6-trimethylphenylboronic acid. (c) 2007 Elsevier B.V. All rights reserved.