C-Amino-1,2,4-triazoles are challenging polynitrogen substrates for metal-catalyzed arylation due to their multidentate character,enhanced coordinating ability and decreased nucleophilicity of the amino group.In the p...C-Amino-1,2,4-triazoles are challenging polynitrogen substrates for metal-catalyzed arylation due to their multidentate character,enhanced coordinating ability and decreased nucleophilicity of the amino group.In the present study,the Buchwald-Hartwig cross-coupling of diverse 3(5)-amino-1,2,4-triazoles with aryl chlorides and bromides delivering(hetero)arylamino-1,2,4-triazoles in good-to-excellent yields under Pd/NHC catalysis was developed.The use of Pd complexes with bulky NHC ligands such as IPr^(*OMe) and TPEDO(1,1,2,2-tetraphenylethane-1,2-diol)as an in situ Pd(Ⅱ)to Pd(0)reductant enabled the selective arylation of the NH_(2) group even in acidic NH unprotected substrates and deactivated 1-substituted 5-amino-and 4-substituted 3-amino-1,2,4-triazoles.The reaction mechanism and structure-activity relationships were studied with DFT calculations.A significant effect of the position of the N-substituent in the 1,2,4-triazole ring on the favorable reaction pathways was revealed.展开更多
Complexes of Pd(Ⅱ)with NHC ligands can suffer facile decomposition in the presence of alkali metal hydroxides,alkoxydes and other strong oxygen-containing bases via the reductive elimination of the NHC and Pd-coordin...Complexes of Pd(Ⅱ)with NHC ligands can suffer facile decomposition in the presence of alkali metal hydroxides,alkoxydes and other strong oxygen-containing bases via the reductive elimination of the NHC and Pd-coordinated base anion,the so-called O-NHC coupling.O-NHC coupling can represent a serious problem for the stability of Pd/NHC catalytic systems in numerous practically important reactions conducted in the presence of bases.In the present study,a new approach to stabilizing the Pd-NHC bond against cleavage by strong bases was developed.展开更多
The aim of the present study was to explore the transformations of heteroleptic and homoleptic Au(I)complexes in detail and to systematically map their chemical evolutionary pathways.The relationships between these Au...The aim of the present study was to explore the transformations of heteroleptic and homoleptic Au(I)complexes in detail and to systematically map their chemical evolutionary pathways.The relationships between these Au(I)complexes and the formation of gold nanoparticles and between the leaching processes of Au species from nanoparticles by NHC carbenes were studied.Moreover,Au-based reaction systems exhibit a wide variety of gold complexes and metallic gold particles depending on the conditions.The evolutionary pathways and transformations of homoleptic and heteroleptic Au(I)complexes were mapped using NMR,ESI-HRMS and electron microscopy.Depending on the conditions,a diverse range of metallic gold nanoparticles was formed.Interestingly,the formation of an NHC-Au(I)complex during the leaching of Au species from metallic nanoparticles in the presence of NHC carbenes was also noted.Our findings illustrate that the composition of Au-based reaction systems can simultaneously include various gold complexes and gold particles,reinforcing the potential of gold complexes to activate and transform molecules in a variety of reactions.By studying and understanding the physical and chemical properties of NHC-Au(I)complexes and the transformations they undergo under various conditions,we provide new opportunities for future research using gold-based systems for the development of dynamic catalytic systems.展开更多
基金supported by the Russian Science Foundation(RSF grant 22-23-00380).
文摘C-Amino-1,2,4-triazoles are challenging polynitrogen substrates for metal-catalyzed arylation due to their multidentate character,enhanced coordinating ability and decreased nucleophilicity of the amino group.In the present study,the Buchwald-Hartwig cross-coupling of diverse 3(5)-amino-1,2,4-triazoles with aryl chlorides and bromides delivering(hetero)arylamino-1,2,4-triazoles in good-to-excellent yields under Pd/NHC catalysis was developed.The use of Pd complexes with bulky NHC ligands such as IPr^(*OMe) and TPEDO(1,1,2,2-tetraphenylethane-1,2-diol)as an in situ Pd(Ⅱ)to Pd(0)reductant enabled the selective arylation of the NH_(2) group even in acidic NH unprotected substrates and deactivated 1-substituted 5-amino-and 4-substituted 3-amino-1,2,4-triazoles.The reaction mechanism and structure-activity relationships were studied with DFT calculations.A significant effect of the position of the N-substituent in the 1,2,4-triazole ring on the favorable reaction pathways was revealed.
基金supported by the Russian Science Foundation,RSF grant 19-73-10100(studies of Pd/NHC complex stability and catalytic activity)by the Ministry of Science and Higher Education of the Russian Federation,project 2019-0990(synthesis of Pd/NHC complexes).
文摘Complexes of Pd(Ⅱ)with NHC ligands can suffer facile decomposition in the presence of alkali metal hydroxides,alkoxydes and other strong oxygen-containing bases via the reductive elimination of the NHC and Pd-coordinated base anion,the so-called O-NHC coupling.O-NHC coupling can represent a serious problem for the stability of Pd/NHC catalytic systems in numerous practically important reactions conducted in the presence of bases.In the present study,a new approach to stabilizing the Pd-NHC bond against cleavage by strong bases was developed.
文摘The aim of the present study was to explore the transformations of heteroleptic and homoleptic Au(I)complexes in detail and to systematically map their chemical evolutionary pathways.The relationships between these Au(I)complexes and the formation of gold nanoparticles and between the leaching processes of Au species from nanoparticles by NHC carbenes were studied.Moreover,Au-based reaction systems exhibit a wide variety of gold complexes and metallic gold particles depending on the conditions.The evolutionary pathways and transformations of homoleptic and heteroleptic Au(I)complexes were mapped using NMR,ESI-HRMS and electron microscopy.Depending on the conditions,a diverse range of metallic gold nanoparticles was formed.Interestingly,the formation of an NHC-Au(I)complex during the leaching of Au species from metallic nanoparticles in the presence of NHC carbenes was also noted.Our findings illustrate that the composition of Au-based reaction systems can simultaneously include various gold complexes and gold particles,reinforcing the potential of gold complexes to activate and transform molecules in a variety of reactions.By studying and understanding the physical and chemical properties of NHC-Au(I)complexes and the transformations they undergo under various conditions,we provide new opportunities for future research using gold-based systems for the development of dynamic catalytic systems.
