Synthesis and structural and conformational study of some esters derived from 8-β-hydroxy-3-phenethyl-3-azabicyclooctan-8-α-carboxylic acid

Article abstract of DOI:10.1016/0022-2860(91)85068-E

A series of 8-β-hydroxy-8-α-alkoxycarbonyl-N-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-β-hydroxy-3-phenethyl-3-azabicyclo<3.2.1>octan-8-α-carboxylate (Va) has been determined by X-ray diffraction.In deuterochloroform and deuterobenzene the cyclopentane and piperidine rings of the title compounds show an envelope conformation flattened at C8 and a distorted chair conformation puckered at C8 and flattened at N3, respectively, with the N-substituent in an equatorial position.These results are in close agreement with that found for compound Va in the crystalline state.By comparing the NMR and X-ray parameters of the title compounds with those of the corresponding 8-α-hydroxy-8-β-alkoxycarbonyl-N-phenethyl-3-azabicyclo<3.2.1>octane epimers and 3-phenethyl-3-azabicyclo<3.2.1>octan-8-α- (and β)ol, several stereoelectronic effects have been deduced.