Quinolizidines. Part IV. The cyclopenta[ij]quinolizidines

Abstract

Syntheses of the three stereoisomeric cyclopenta[ij]quinolizidines from 2-(2′-cyanoethyl)-5-(2′-ethoxycarbonylethyl)cyclopentanone are described. Δ¹⁰⁽¹¹⁾Dehydrocyclopenta[ij]quinolizldine is also described, and its reduction to the saturated bases.

The stereochemistry of the three cyclopenta[ij]quinolizidines is established from infrared spectroscopy, from the reluctance shown by cis, cis-cyclopentaquinolizidine to undergo quaternisation, and from the partial optical resolution of the cis,trans-isomer.