Synthesis and structural and conformational study of some esters derived from 8-α-hydroxy-3-phenethyl-3-azabicyclo [3.2.1] octan-8-β-carboxylic acid

Abstract

A series of 8-β-alcoxycarbonyl-8-α-hydroxy-3-phenethyl-3-azabicyclo[3.2.1]octane derivatives have been synthesized and studied by IR, 1H and 13C NMR spectroscopy, and the crystal structure of ethyl-8-α-hydroxy-3-azabicyclo[3.2.1]octane-8-β-carboxylate ( VI) has been determined by X-ray diffraction. The compounds studied display in deuterochloroform and benzene- d 6 the same preferred chair-envelope conformation flattened at N-8 and puckered at C-3 with both the phenethyl and hydroxy groups in the equatorial position with respect to the piperidine ring. These results are in close agreement with those found for compound VI in the crystalline state. By comparing the NMR parameters of these compounds with those of 3-phenethyl-3-azabicyclo [3.2.1]octan-8-α-ol ( VII) several stereoelectronic effects have been deduced.