The structure of a new alkaloid isolated from Piper peepuloides has been revised as 2-methoxy-4,5-methylenedioxy-cis-cinnamoylpiperidide. The revision is based upon spectral evidence and syntheses of both isomers. The synthesis of the cis isomer has been accomplished through an intermediate obtained by a novel ring opening of the coumarin 'ayapin' using sodium hydride and methyl iodide in tetrahydrofuran. © 1979.