Regio- and Chemoselective Multiple Functionalization of Chloropyrazine Derivatives. Application to the Synthesis of Coelenterazine
作者:Marc Mosrin、Tomke Bresser、Paul Knochel
DOI:10.1021/ol901275n
日期:2009.8.6
Successive regio- and chemoselective metalations of chloropyrazines using TMPMgCl·LiCl and TMPZnCl·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.
A broad range of functionalized aryl- and heteroarylzinc reagents were preparedvia directed zincation of sensitive and moderately activated aromatics and heteroaromatics using TMPZnCl·LiCl under various reaction conditions. Diverse sensitive functional groups such as a nitro group, an aldehyde, an ester, and a nitrile are readily tolerated and are compatible with high metalation temperatures. Furthermore