The direct conversion of cheap syngas into value-added ethanol at an industrial scale is in high demand.Herein we disclose a one-pot homogeneous homologation of methanol to ethanol with syngas via a rhodium/ruthenium ...The direct conversion of cheap syngas into value-added ethanol at an industrial scale is in high demand.Herein we disclose a one-pot homogeneous homologation of methanol to ethanol with syngas via a rhodium/ruthenium bimetallic catalytic approach.By introducing a catalytic amount of methyl iodide,methanol can be converted to ethanol with high selectivity(>91%ethanol).A syngas ratio of H_(2)/CO=4:1 was found to be optimal.Among various phosphine ligands tested,Rh-dppp catalyst gave the highest aldehyde pathway selectivity,thus providing an effective route for the synthesis of ethanol upon coupling with a Ru hydrogenation catalyst.The bite angle of the bisphosphine ligands dramatically influences the selectivity of the dual Rh/Ru metallic cascade catalysts.In line with the experimental findings,theoretical calculations predicted a rational trend of the selectivity of different bisphosphine ligands via varying bite angle properties.展开更多
3(R)-(t-Butyldiphenylsilyloxy)-1-penten-4-yne was prepared using D-xylose as the chiral template via an improved procedure for aldehyde-to-alkyne homologation in high yield.
A convenient rhodium catalyzed oxidative arene homologation of aniline derivatives with symmetrical or unsymmetrical alkynes using Cu(OAc)2 as oxidant is described. Urea group is shown to be effective as a directing...A convenient rhodium catalyzed oxidative arene homologation of aniline derivatives with symmetrical or unsymmetrical alkynes using Cu(OAc)2 as oxidant is described. Urea group is shown to be effective as a directing group for initial ortho C–H activation. Two migratory insertion events of alkyne into Rh–C bond occur successively, both with complete regioselectivity. This method is particularly useful for synthesis of polyarenes with different substituents, which has not been reported with conventional protocol. A mechanism has been proposed to explain the observed data.展开更多
Homologation of protected taxol side chen 8 from 4 was accomplished stereospecifically through the key intermediate diazo ketone 5 which was actually isolated. The structures of 5 and 7 were identified by spectrometri...Homologation of protected taxol side chen 8 from 4 was accomplished stereospecifically through the key intermediate diazo ketone 5 which was actually isolated. The structures of 5 and 7 were identified by spectrometric methods, mainly 1H-NMR, 1R, 13C-NMR and DEPT techniques.展开更多
基金This experimental investigation was financially supported by the National Natural Science Foundation of China(grant no.21991113)the Guangdong Provincial Key Laboratory of Catalysis(grant no.2020B121201002)+1 种基金the Science,Technology,and Innovation Commission of Shenzhen(grant no.20200925161222002)Theoretical calculations were supported by the National Natural Science Foundation of China(grant nos.22033005 and 22103035).
文摘The direct conversion of cheap syngas into value-added ethanol at an industrial scale is in high demand.Herein we disclose a one-pot homogeneous homologation of methanol to ethanol with syngas via a rhodium/ruthenium bimetallic catalytic approach.By introducing a catalytic amount of methyl iodide,methanol can be converted to ethanol with high selectivity(>91%ethanol).A syngas ratio of H_(2)/CO=4:1 was found to be optimal.Among various phosphine ligands tested,Rh-dppp catalyst gave the highest aldehyde pathway selectivity,thus providing an effective route for the synthesis of ethanol upon coupling with a Ru hydrogenation catalyst.The bite angle of the bisphosphine ligands dramatically influences the selectivity of the dual Rh/Ru metallic cascade catalysts.In line with the experimental findings,theoretical calculations predicted a rational trend of the selectivity of different bisphosphine ligands via varying bite angle properties.
文摘3(R)-(t-Butyldiphenylsilyloxy)-1-penten-4-yne was prepared using D-xylose as the chiral template via an improved procedure for aldehyde-to-alkyne homologation in high yield.
基金the National Natural Science Foundation of China (No. 21272077)the Natural Science Foundation of Jiangsu Province (No. BK20131143)Jiangsu Key Laboratory of Advanced Catalytic Materials & Technology and the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)
文摘A convenient rhodium catalyzed oxidative arene homologation of aniline derivatives with symmetrical or unsymmetrical alkynes using Cu(OAc)2 as oxidant is described. Urea group is shown to be effective as a directing group for initial ortho C–H activation. Two migratory insertion events of alkyne into Rh–C bond occur successively, both with complete regioselectivity. This method is particularly useful for synthesis of polyarenes with different substituents, which has not been reported with conventional protocol. A mechanism has been proposed to explain the observed data.
文摘Homologation of protected taxol side chen 8 from 4 was accomplished stereospecifically through the key intermediate diazo ketone 5 which was actually isolated. The structures of 5 and 7 were identified by spectrometric methods, mainly 1H-NMR, 1R, 13C-NMR and DEPT techniques.