A New Synthetic Method of Cyclic Nitrogenous Compounds. XV. : Syntheses of 1, 2, 4, 4a, 5, 6, 7, 7a-Octahydropyrrolo [2, 1, 5-cd] indolizine Derivatives

Abstract

Dry distillation of ethyl 3-oxoindolizidine-5-propionate (I) with the same amount of soda lime as reported previously affords 1, 2, 4, 4a, 5, 6, 7, 7a-octahydropyrrolo [2, 1, 5-cd] -indolizine (II) in 48% yield. In order to confirm the α, β-enamine structure of II, conc. potassium cyanide solution was added dropwise with stirring to a solution of the perchlorate (III) of II. In this case, the cyano compound (IV) was also obtained in a quantitative yield. Attempted recrystallization of the picrate of IV from hot ethanol yielded the picrate of II by elimination of hydrocyanic acid as shown in Chart 1.