The formation and the presence of hypervalent Si in the electron donor-acceptor com- plex H_3N·SiH_3 Cl have been investigated by ab initio calculation. The results show that there is a 0.707eV decrease of energy...The formation and the presence of hypervalent Si in the electron donor-acceptor com- plex H_3N·SiH_3 Cl have been investigated by ab initio calculation. The results show that there is a 0.707eV decrease of energy when the complex H_3N.SiH_3 Cl is formed from NH_3 and H_3SiCl, the interaction potential between the donor NH_3 and the acceptor H_3SiCl belongs to the Morse type, and the bond angle A(H-Si-Cl) versus bond length d(N-Si) presents a linear relation. The results also show that the interaction is mainly from giving the lone pair electrons in HOMO of NH_3 to LUMO of H_3SiCl, in which the 2P_z of N and the 3d_0 of Si play important role. Bond N-Si is a weak n-σ*type dative one.展开更多
While N-alkenoxypyridinium salts are widely used for the synthesis ofα-functionalized ketones via umpolung strategy,such approaches are usually limited to special nucleophiles at high temperatures.Herein,we developed...While N-alkenoxypyridinium salts are widely used for the synthesis ofα-functionalized ketones via umpolung strategy,such approaches are usually limited to special nucleophiles at high temperatures.Herein,we developed an alternative photoinduced N-heterocyclic carbene(NHC)-mediated functionalization of N-alkenoxypyridinium salts with various nucleophiles,including tetramethylammonium azide,secondary amines,aryl and alkyl thiols,and even the challenging C(sp^(3))-nucleophiles,under mild conditions.A cascade radical-radical coupling/nucleophilic substitution sequence was proposed,wherein the NHC enabled the formation of a photoactive electron donor-acceptor complex forα-iodo ketone synthesis.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
文摘The formation and the presence of hypervalent Si in the electron donor-acceptor com- plex H_3N·SiH_3 Cl have been investigated by ab initio calculation. The results show that there is a 0.707eV decrease of energy when the complex H_3N.SiH_3 Cl is formed from NH_3 and H_3SiCl, the interaction potential between the donor NH_3 and the acceptor H_3SiCl belongs to the Morse type, and the bond angle A(H-Si-Cl) versus bond length d(N-Si) presents a linear relation. The results also show that the interaction is mainly from giving the lone pair electrons in HOMO of NH_3 to LUMO of H_3SiCl, in which the 2P_z of N and the 3d_0 of Si play important role. Bond N-Si is a weak n-σ*type dative one.
基金financial support from the National Natural Science Foundation of China (No. 22001248)the Fundamental Research Funds for the Central Universities and the University of the Chinese Academy of Sciences
文摘While N-alkenoxypyridinium salts are widely used for the synthesis ofα-functionalized ketones via umpolung strategy,such approaches are usually limited to special nucleophiles at high temperatures.Herein,we developed an alternative photoinduced N-heterocyclic carbene(NHC)-mediated functionalization of N-alkenoxypyridinium salts with various nucleophiles,including tetramethylammonium azide,secondary amines,aryl and alkyl thiols,and even the challenging C(sp^(3))-nucleophiles,under mild conditions.A cascade radical-radical coupling/nucleophilic substitution sequence was proposed,wherein the NHC enabled the formation of a photoactive electron donor-acceptor complex forα-iodo ketone synthesis.
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.
