Authors: LIANGRU YANG, HUANYU BIAN, WENPENG MAI, PU MAO, YONGMEI XIAO, DONG WEI, LINGBO QU
Abstract: A series of asymmetrical substituted tetrahydropyrimidinium salts and different kinds of bridged bis-tetrahydropyrimidinium salts were prepared through the quaterization of tetrahydropyrimidine or the dehydrogenation of hexahydropyrimidine. They were characterized and used as NHC precursors in the palladium catalyzed Buchwald--Hartwig amination reaction. The in situ formed catalytic system Pd(OAc)_2/tetrahydropyrimidinium and ^tBuOK catalyzed the amination of heteroaryl halides and heterocyclic amines effectively, producing the heterocyclic amine functionalized heteroaryl derivatives in high yields.
Keywords: Tetrahydropyrimidinium salt, Buchwald--Hartwig amination, microwave irradiation, palladium catalysis, N-heterocyclic carbene
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