Herein we report the application of a Co(II)PNN^(H) pincer catalyst system(PNN^(H)=2-(5-(t-butyl)-1Hpyrazol-3-yl)-6-(dialkylphosphinomethyl)pyridine)for the highly E-selective transfer semihydrogenation of internal di...Herein we report the application of a Co(II)PNN^(H) pincer catalyst system(PNN^(H)=2-(5-(t-butyl)-1Hpyrazol-3-yl)-6-(dialkylphosphinomethyl)pyridine)for the highly E-selective transfer semihydrogenation of internal diaryl alkynes using methanol and ammonia borane as hydrogen donors.The catalyst system is highly active(short reaction times,low Co concentration)and operates at very mild conditions(low temperature and transfer hydrogenation conditions).Spectroscopic and computational studies suggest that catalysis occurs via the Co(II)oxidation state,most likely with a Co(II)hydride as the key intermediate.Computational analysis of the reaction mechanism further rationalises the selective formation of E-alkenes and the absence of overreduction to produce alkanes.展开更多
基金support by the DFG(project code 419924354)is gratefully acknowledged.
文摘Herein we report the application of a Co(II)PNN^(H) pincer catalyst system(PNN^(H)=2-(5-(t-butyl)-1Hpyrazol-3-yl)-6-(dialkylphosphinomethyl)pyridine)for the highly E-selective transfer semihydrogenation of internal diaryl alkynes using methanol and ammonia borane as hydrogen donors.The catalyst system is highly active(short reaction times,low Co concentration)and operates at very mild conditions(low temperature and transfer hydrogenation conditions).Spectroscopic and computational studies suggest that catalysis occurs via the Co(II)oxidation state,most likely with a Co(II)hydride as the key intermediate.Computational analysis of the reaction mechanism further rationalises the selective formation of E-alkenes and the absence of overreduction to produce alkanes.
