Structural and conformational study of some N-acylaminonitriles derived from 3β-amino-3α-cyano-8-methyl(or benzyl)-8-azabiciclo[3.2.1]octane

Abstract

A series of N′-acyl derivatives of 3β-amino-3α-cyano-N8-substituted nortropanes has been synthesized and studied by NMR spectroscopy, and the crystal structure of 3α-cyano-3β-(xanten-9-carboxamido)-N-benzylnortropane ( IIId) has been determined by X-ray diffraction. The compounds studied display in CDCl 3 the same preferred conformation. The pyrrolidine and piperidine rings adopt an envelope and a distorted chair conformation, puckered at N8 and flattened at C3, with the N-substituent in equatorial position and the acylamino and cyano groups in pseudo-equatorial and pseudo-axial positions respectively. As regards the bicyclic system, these results are in close agreement with those found for compound IIId in the crystalline state. The crystal structure is stabilized by means of N-H…O (amide) intermolecular hydrogen bonds.