We herein report an effective hydrosilylation of 1,1-disubstituted allenes with a palladium catalyst modified by a monophosphorus ligand,leading to a series ofα-tertiary allylsilanes in high yields and exceptional re...We herein report an effective hydrosilylation of 1,1-disubstituted allenes with a palladium catalyst modified by a monophosphorus ligand,leading to a series ofα-tertiary allylsilanes in high yields and exceptional regiose-lectivities.The employment of BI-DIME is essential for the high reactivities and selectivities.A chiralα-tertiary allylsilane is formed in excellent ee for the first time by employing a chiral monophosphorus ligand.展开更多
Sterically congestedα-tertiary primary amines are ubiquitous substructures in pharmaceutical and agrochemical agents yet are challenging to access.Herein,straightforward photoredox-catalyzed access to structurally di...Sterically congestedα-tertiary primary amines are ubiquitous substructures in pharmaceutical and agrochemical agents yet are challenging to access.Herein,straightforward photoredox-catalyzed access to structurally diverseα,α,α-trisubstituted primary amines from denitrogenative alkylarylation or dialkylation of vinyl azides with N-hydroxyphthalimide(NHPI)esters and cyanoarenes or aryl aldehydes has been developed.The use of vinyl azide as a precursor to a primary aminewas enabled by the dual role of the Hantzsch ester to form an electron donor-acceptor complex and serve as a sacrificial reductant.This strategy provides a modular synthesis ofα-tertiary primary amines,including unprotected 1,2-amino alcohols,from simple materials with excellent functional group tolerance.The synthetic applicability of this method was demonstrated by streamlined access to 2,2-disubstituted tetrahydroquinolines.Preliminary investigations support two parallel reductive photocatalytic cycles allowing for the denitrogenative alkylarylation or dialkylation of vinyl azides via decarboxylative radical addition followed by heteroradical cross-coupling betweenα-amino radicals and aryl anion radicals or ketyl anion radicals.展开更多
Since tertiary amines (Cα-H) can be oxidized by peroxides and transition metal cations in high oxidation states into Ca2+ radicals to initiate vinylic polymerizations of methacrylates, Cu2+ and 2-(N,N-dimethylam...Since tertiary amines (Cα-H) can be oxidized by peroxides and transition metal cations in high oxidation states into Ca2+ radicals to initiate vinylic polymerizations of methacrylates, Cu2+ and 2-(N,N-dimethylamino)ethyl methacrylate (DMAEMA) form a polymerizable redox initiating pair, in which DMAEMA serves as an intrinsically reducing inimer. CuSOa-catalyzed aqueous self-initiated radical polymerizations of DMAEMA were successfully performed at ambient temperature via a continuous Cu2+-tertiary amine redox initiation based on catalyst regeneration in the presence of O2. The polymerization kinetics was monitored by gas chromatography and the structure of PDMAEMA was characterized by gel- permeation chromatography, nuclear magnetic resonance spectroscopy, laser light scattering and online intrinsic-viscosity analysis. Both the monomer conversion and the molecular weight of PDMAEMA increase with the reaction while the molecular weight distribution maintains rather broad, as the Cu2+-DMAEMA redox-initiation leads to linear PDMAEMA chains with terminal methacryloxyl moieties, and the Cu2+-PDMAEMA redox-initiation results in branched chains. The branched topology forms and develops only for the high-MW components of the PDMAEMA. Our results provide a facile strategy to prepare branched polymers from such commercially available intrinsically reducing inimers using a negligible concentration of regenerative air-stable catalysts.展开更多
基金We are grateful for financial support from the Strategic Priority Research Program of the Chinese Academy of Sciences(Nos.XDB20000000)Chinese Academy of Sciences(No.QYZDY-SSWSLH029)+1 种基金National Natural Science Foundation of China(Nos.21725205,21432007,21572246 and 21702223)the K.C.Wong Education Foundation.
文摘We herein report an effective hydrosilylation of 1,1-disubstituted allenes with a palladium catalyst modified by a monophosphorus ligand,leading to a series ofα-tertiary allylsilanes in high yields and exceptional regiose-lectivities.The employment of BI-DIME is essential for the high reactivities and selectivities.A chiralα-tertiary allylsilane is formed in excellent ee for the first time by employing a chiral monophosphorus ligand.
基金This research was made possible as a result of a generous grant from NSFC(grant nos.21971101 and 22171127)Guangdong Basic and Applied Basic Research Foundation(grant no.2022A1515011806)+3 种基金Department of Education of Guangdong Province(grant nos.2022JGXM054 and 2021KTSCX106)Shenzhen Science and Technology Innovation Committee(grant no.JCYJ20220519201425001)Thousand Talents Program for Young Scholars,The Pearl River Talent Recruitment Program(grant no.2019QN01Y261)Guangdong Provincial Key Laboratory of Catalysis(grant no.2020B121201002).
文摘Sterically congestedα-tertiary primary amines are ubiquitous substructures in pharmaceutical and agrochemical agents yet are challenging to access.Herein,straightforward photoredox-catalyzed access to structurally diverseα,α,α-trisubstituted primary amines from denitrogenative alkylarylation or dialkylation of vinyl azides with N-hydroxyphthalimide(NHPI)esters and cyanoarenes or aryl aldehydes has been developed.The use of vinyl azide as a precursor to a primary aminewas enabled by the dual role of the Hantzsch ester to form an electron donor-acceptor complex and serve as a sacrificial reductant.This strategy provides a modular synthesis ofα-tertiary primary amines,including unprotected 1,2-amino alcohols,from simple materials with excellent functional group tolerance.The synthetic applicability of this method was demonstrated by streamlined access to 2,2-disubstituted tetrahydroquinolines.Preliminary investigations support two parallel reductive photocatalytic cycles allowing for the denitrogenative alkylarylation or dialkylation of vinyl azides via decarboxylative radical addition followed by heteroradical cross-coupling betweenα-amino radicals and aryl anion radicals or ketyl anion radicals.
基金financially supported by the National Natural Science Foundation of China(No.20674033)Natural Science Foundation of Jiangsu Province(No.BK2008142)Scientific Research Foundation for the Returned Overseas Chinese Scholars(State Education Ministry)
文摘Since tertiary amines (Cα-H) can be oxidized by peroxides and transition metal cations in high oxidation states into Ca2+ radicals to initiate vinylic polymerizations of methacrylates, Cu2+ and 2-(N,N-dimethylamino)ethyl methacrylate (DMAEMA) form a polymerizable redox initiating pair, in which DMAEMA serves as an intrinsically reducing inimer. CuSOa-catalyzed aqueous self-initiated radical polymerizations of DMAEMA were successfully performed at ambient temperature via a continuous Cu2+-tertiary amine redox initiation based on catalyst regeneration in the presence of O2. The polymerization kinetics was monitored by gas chromatography and the structure of PDMAEMA was characterized by gel- permeation chromatography, nuclear magnetic resonance spectroscopy, laser light scattering and online intrinsic-viscosity analysis. Both the monomer conversion and the molecular weight of PDMAEMA increase with the reaction while the molecular weight distribution maintains rather broad, as the Cu2+-DMAEMA redox-initiation leads to linear PDMAEMA chains with terminal methacryloxyl moieties, and the Cu2+-PDMAEMA redox-initiation results in branched chains. The branched topology forms and develops only for the high-MW components of the PDMAEMA. Our results provide a facile strategy to prepare branched polymers from such commercially available intrinsically reducing inimers using a negligible concentration of regenerative air-stable catalysts.