A convenient synthesis of 8‐substituted indolizines as precursors to 5‐substituted cycl{3.2.2}azine derivatives

Abstract The synthesis of 8‐substituted indolizines is described via a two step process in which a 1,4‐diketone, containing a rerf‐butyl group, is cyclocondensed with a trialkylsilyl protected pyrrole to provide 5,8‐disubstituted indolizines in higher yields than the identical reaction with unprotected pyrrole. Cleavage of the tert‐butyl group from the indolizine 5‐position, by treatment with 85% phosphoric acid, provides 8‐substituted indolizines in good yields. Treatment of 8‐substituted indolizines with dimethyl acetylenedicarboxylate, in the presence of palladium‐on‐carbon, provides novel 5‐substituted cycl{3.2.2) derivatives.