Optical rotatory dispersion and absolute configuration. Part 35. Chiroptical properties and conformation of indolizidine

Abstract

¹ H N.m.r. spectroscopy at 360 MHz confirms that indolizidine is trans-fused with the piperidine ring in a chair conformation. The pyrrolidine ring adopts an envelope conformation with the nitrogen atom displaced out of the plane of the four carbon atoms of the ring. An improved synthesis of (+)- and (–)-indolizidine from (–)-and (+)-coniine is described. The o.r.d. and c.d. spectra of indolizidine are compared with those of coniine.