Hydroaminoalkylation of Alkenes Catalyzed by AlkyltitaniumComplexes

摘要

α-Branched alkylamines are one of key and widespread structural motifs in natural productsand biologically active compounds.It is in high demand to develop an efficient method forsynthesizing functionalized alkylamines in an environmentally friendly process.One of idealmethods is hydroaminoalkylation of alkenes via α-C-H bond activation of alkylamines usingearly transition metal catalysts;;Nugent et al.reported that homoleptic amide complexes ofniobium and tantalum,M(NMe2)5 (M = Nb and Ta),showed catalytic reactivity forhydroaminoalkylation using HNMe2,1 and,later,Hartwig et al.demonstrated that a moreelectrophilic group 5 metal complex,[TaCl3(NEt2)2]2,became a superior catalyst forhydroaminoalkylation with alkylamines.Further development of the aminoalkylation hasbeen achieved by Schafer et al.and Doye et al,respectively,using amidato and amidinatocomplexes of early transiton metals for improving the catalytic activity,though harsh reactioncondition and/or longer reaction time were still required.Herein,we report a new and moreactive catalyst system based on cationic half-titanocene complexes for hydroaminoalkylationof olefins with N-methylaniline at room temperature.