Concise Synthesis of v-Coelenterazines

A novel synthetic method for v-coelenterazine (v-CTZ), which is a vinylene-bridged analog of native CTZ with a large red-shifted luminescence property, is described. The synthesis was achieved in a concise way through the use of three sequential cross-coupling reactions and ring-closing metathesis (RCM). A newly synthesized C2-modified trifluoromethyl analog cf3-v-CTZ showed slightly more red-shifted luminescence than v-CTZ when it was used as a substrate for Renilla luciferases.