Organolanthanide-catalyzed intra- and intermolecular carbon-nitrogen and carbon-carbon bond-forming reactions.

摘要

Organolanthanides of the type L{dollar}sb2{dollar}LnR (L = {dollar}etasp5{dollar}-cyclopentadienyl-type ancillary ligand) serve as efficient precatalysts for the regioselective intramolecular hydroamination/cyclization and bicyclization, as well as intermolecular hydroamination and cyclization of a diverse variety of olefins and alkynes with primary and secondary amines to yield the corresponding pyrrole, pyrrolizidine, indolizidine, amine, imine and pyrazine derivatives.; For intramolecular amino-alkyne catalytic processes, cyclization of amino-alkynes RC{dollar}equiv{dollar}C(CH{dollar}sb2)sb{lcub}rm a{rcub}{dollar}NHR{dollar}spprime{dollar} (R = Ph, Me, CH{dollar}sb2{dollar}=CMeCH{dollar}sb2{dollar}, H, SiMe{dollar}sb3{dollar}; n = 3, 4, 5; R{dollar}spprime{dollar} = SiMe{dollar}sb3{dollar}, H; R{dollar}sb1{dollar} = allyl,4-pentenyl) yields the corresponding cyclic imines RCH{dollar}sb2{dollar}C=N(CH{dollar}sb2)sb{lcub}rm a-1{rcub}{dollar}CH{dollar}sb2{dollar}, and heterocycles RCH=CNR{dollar}spprime{dollar}(CH{dollar}sb2)sb{lcub}rm a-1{rcub}{dollar}CH{dollar}sb2{dollar}. The use of larger metal ionic radius and more open L{dollar}sb2{dollar}Ln- as the catalysts results in a decrease in the cyclization rate, arguing that the steric demands in the insertion transition state are relaxed compared to the analogous amino-olefin transformations.; In the case of intramolecular bicyclization processes, the substrates RC{dollar}equiv{dollar}C-(CH{dollar}sb2)sb{lcub}rm a{rcub}{dollar}NH(CH{dollar}sb2)sb{lcub}rm b{rcub}{dollar}C{dollar}equiv{dollar}CR, RC{dollar}equiv{dollar}C(CH{dollar}sb2)sb{lcub}rm c{rcub}{dollar}NH(CH{dollar}sb2)sb{lcub}rm d{rcub}{dollar}CH=CH{dollar}sb2{dollar}, and H{dollar}sb2{dollar}C=CH(CH{dollar}sb2)sb{lcub}rm e{rcub}{dollar}NH-CH{dollar}sb2)sb{lcub}rm f{rcub}{dollar}CH=CH{dollar}sb2{dollar} are regioselectively bicyclized to the corresponding pyrrolizidine and indolizidine skeletons. Kinetic and mechanistic evidence suggests a turnover-limiting alkene/alkyne insertion into the Ln-N {dollar}alpha{dollar}-bond occurring first, followed by a rapid pendent unsaturated carbon-carbon multiple bond insertion into the resulting Ln-C bond before the protonolysis to generate the new C-N and C-C bonds in a single catalytic cycle.; The present catalysts are also employed for the regioselective intermolecular hydroamination of alkynes R{dollar}spprime{dollar}-C{dollar}equiv{dollar}C-Me (R{dollar}spprime{dollar} = SiMe{dollar}sb3{dollar}, C{dollar}sb6{dollar}H{dollar}sb5{dollar}, Me), alkenes R-CH=CH{dollar}sb2{dollar} (R = SiMe{dollar}sb3{dollar}, n-Pr, CH{dollar}sb2{dollar}=CH) with amines R{dollar}sp{lcub}primeprime{rcub}{dollar}NH{dollar}sb2{dollar} (R{dollar}sp{lcub}primeprime{rcub}{dollar} = n-Pr, n-Bu, i-Bu) to yield the corresponding imines E-R{dollar}spprime{dollar}CH{dollar}sb2{dollar}C(Me)=NR{dollar}sp{lcub}primeprime{rcub}{dollar}, amines Me{dollar}sb3{dollar}SiCH{dollar}sb2{dollar}CH{dollar}sb2{dollar}NHR{dollar}sp{lcub}primeprime{rcub}{dollar}, CH{dollar}sb3{dollar}CH{dollar}sb2{dollar}CH{dollar}sb2{dollar}CH(NHR{dollar}sp{lcub}primeprime{rcub}{dollar})CH{dollar}sb3{dollar}, and E-CH{dollar}sb3{dollar}CH=CHCH{dollar}sb2{dollar}NHR{dollar}sp{lcub}primeprime{rcub}{dollar}, respectively. Turnover frequencies are {dollar}sim{dollar}1/1000 those of the intramolecular analogues under the comparable reaction conditions. For L{dollar}sb2{dollar}Nd-mediated addition of n-BuNH{dollar}sb2{dollar} with Me{dollar}sb3{dollar}Si-C{dollar}equiv{dollar}C-Me, the reaction kinetics are zero-order in (amine), first-order in both (catalyst) and (alkyne) with {dollar}Delta{dollar}H{dollar}sp{lcub}not={rcub}{dollar} = 17.2 (1.1) kcal mol{dollar}sp{lcub}-l{rcub}{dollar}, {dollar}Delta Ssp{lcub}not={rcub} = -25.9 (9.7){dollar} eu. When using HC{dollar}equiv{dollar}CCH{dollar}sb2{dollar}NHR as both amines and substrates, the