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
The synthesis and full characterization of several transition metal complexes of a redox-switchable,biaryl(Ar^(T))-substituted[1]phosphaferrocenophane,FcPAr^(T)(L2),in conjunction with some palladium complexes of the ...The synthesis and full characterization of several transition metal complexes of a redox-switchable,biaryl(Ar^(T))-substituted[1]phosphaferrocenophane,FcPAr^(T)(L2),in conjunction with some palladium complexes of the mesityl(Mes)-substituted derivative,FcPMes(L1),and the non-bridged diphenylferrocenyl phosphine,Ph_(2)PFc(L3),are reported.Cyclic voltammetry studies on the bimetallic complexes[Ir(κ^(1)P-L2)(cod)Cl](1),[Ir(κ^(1)P-L2)(CO)2Cl](2),[AuCl(κ^(1)P-L2)](3),[Pd(κ^(1)P-L2)(η^(3)-allyl)Cl](4),[Pd(κ^(1)P-L3)(η^(3)-allyl)Cl](5),[Pd(κ^(1)P-L3)(2-aminobiphenyl)(SO_(3)CH_(3))](6),and[Pd(κ^(1)P-L1)(2-aminobiphenyl)(SO_(3)CH_(3))](7)provided indications for a good electronic communication between the metal atoms.In order to confirm that the[1]ferrocenophane or 1-ferrocenyl unit might be able to electrochemically influence the reactivity of the coordinated transition metal,the palladium complexes 4-7 were employed as redox-switchable catalysts(RSC)in Buchwald-Hartwig cross-coupling reactions.The catalytic activity depends on the ligand and decreases in the series L3>L2>L1.In stirred solutions,the reaction rate can be influenced by addition of an oxidizing reagent.Some reactions were accelerated with in situ generated,cationic complexes as catalysts as compared to their neutral analogs;in some cases,the activity was found to be lower.Furthermore,steric effects play a predominant role,among other factors.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financial support from the DFG-funded transregional collaborative research centre SFB/TRR 88“Cooperative effects in homo-and heterometallic complexes(3MET)”(project B4).
文摘The synthesis and full characterization of several transition metal complexes of a redox-switchable,biaryl(Ar^(T))-substituted[1]phosphaferrocenophane,FcPAr^(T)(L2),in conjunction with some palladium complexes of the mesityl(Mes)-substituted derivative,FcPMes(L1),and the non-bridged diphenylferrocenyl phosphine,Ph_(2)PFc(L3),are reported.Cyclic voltammetry studies on the bimetallic complexes[Ir(κ^(1)P-L2)(cod)Cl](1),[Ir(κ^(1)P-L2)(CO)2Cl](2),[AuCl(κ^(1)P-L2)](3),[Pd(κ^(1)P-L2)(η^(3)-allyl)Cl](4),[Pd(κ^(1)P-L3)(η^(3)-allyl)Cl](5),[Pd(κ^(1)P-L3)(2-aminobiphenyl)(SO_(3)CH_(3))](6),and[Pd(κ^(1)P-L1)(2-aminobiphenyl)(SO_(3)CH_(3))](7)provided indications for a good electronic communication between the metal atoms.In order to confirm that the[1]ferrocenophane or 1-ferrocenyl unit might be able to electrochemically influence the reactivity of the coordinated transition metal,the palladium complexes 4-7 were employed as redox-switchable catalysts(RSC)in Buchwald-Hartwig cross-coupling reactions.The catalytic activity depends on the ligand and decreases in the series L3>L2>L1.In stirred solutions,the reaction rate can be influenced by addition of an oxidizing reagent.Some reactions were accelerated with in situ generated,cationic complexes as catalysts as compared to their neutral analogs;in some cases,the activity was found to be lower.Furthermore,steric effects play a predominant role,among other factors.
