Introduction of benzyl and p-methoxyphenyl groups to the 2-aminopyrazine nucleus was achieved by direct alkylation and Stille coupling, respectively, to afford the known precursor of coelenterazine. Synthesis of coelenterazine could be completed by the folowing two known steps of demethylation and imidazolone formation. Although this method is shortened by only one or two steps with a moderate yield compared with the known procedure, it allows us to introduce various types of aromatic chromophore.

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