To ensure an efficient and time-saving pallado-catalyzed coupling and easily access starting material 1a, precursor for the subsequent reductive amination, we investigated several reaction conditions by considering solvent, catalyst and equivalent of the diazacycle. Entry 3 was selected because of its low time of reaction and the low amount of piperazine used for the reaction, which was especially suitable for less readily available diazacyles. Synthesis of precursors 1a-b.