Regio- and Chemoselective Multiple Functionalization of Chloropyrazine Derivatives. Application to the Synthesis of Coelenterazine

Successive regio- and chemoselective metalations of chloropyrazines using TMPMgCl center dot LiCl and TMPZnCl center dot LiCl furnish, after trapping with electrophiles, highly functionalized pyrazines in high yields. Application to a synthesis of coelenterazine, a bioluminescent natural product in jellyfish Aequorea victoria, in nine steps (9% overall yield) is reported.