Synthesis of the indole alkaloids meridianins from the tunicate Aplidium meridianum

The marine natural products meridianins A and C-E have been synthesized for the first time starting from the appropriate N-tosyl-3-acetylindole. A fac ile two-step conversion of N-tosyl-3-acetylindoles to the corresponding mer idianins by treatment with dimethylformamide dimethylacetal and further cyc lization of the resulting enaminone with aminoguanidine is described. This method has also been applied for the preparation of the 3-[(2-amino)pyrimid in-4-yl]-7-azaindole. (C) 2001 Elsevier Science Ltd. All rights reserved.