Complete Regioselective Addition of Grignard Reagents to Pyrazine <i>N</i>-Oxides, Toward an Efficient Enantioselective Synthesis of Substituted Piperazines
new one-pot strategy for the synthesis of protected substituted piperazines via the addition of Grignardreagents to pyrazine N-oxides is presented. This strategy is high yielding (33−91% over three steps), step-efficient, and fast. The synthesized N,N-diprotected piperazines are convenient to handle and allow for orthogonal deprotection at either nitrogen for selective transformations. In addition