SYNTHESIS OF PIPERAZINE DERIVATIVES BY Cp~*Ir COMPLEX-CATALYZED N-ALKYLATIVE REACTIONS OF ETHANOLAMINES

摘要

A new method for the synthesis of piperazine derivatives catalyzed by a Cp~*Ir complex has been developed. Cp~*Ir complex-catalyzed N-alkylative homocoupling reactions of N-benzylethanolamines give N,N'-dibenzylpiperazine derivatives. For example, the reaction of N-benzylethanolamine in the presence of [Cp~*IrCl2]2 (2.5 mol%) and NaHCO3 (15 mol%) in toluene at 110 °C for 17 h gives N,N'-dibenzylpiperazine in 66% yield. Cp~*Ir complex-catalyzed N-alkylative cross coupling reactions of Boc-protected diethanolamines with benzylamine also give N-benzyl-N'-Boc-piperazine derivatives in moderate to good yields.