Synthetic studies on the perhydropyrrolo[2,1- j]quinoline marine alkaloids lepadiformine and cylindricine C using a 2-azapentadienyl anion cycloaddition. Synthesis of 2,13-diepilepadiformine (or 2-epi-11-deoxycylindricine C)

Abstract

Tin-lithium exchange of 13 with n-BuLi produced the 2-azapentadienyl anion 6 (R = CH 3), which participated in a [π4s+π2s] cycloaddition reaction with phenyl vinyl sulfide to afford the spirocyclic pyrrolidine 14, which as coverted to 2,13-diepilepadiformine (or 2-epi-11-deoxycylindricine C) 17 by a sequence of steps involving oxidative cleavage of the propenyl side-chain, intramolecular reductive amination, and desulfurization.