H NMR spectroscopy was used to establish that 7-alkoxyalkyl-3-thia-7-azabicyclo[3.3.1]nonan-9-onesand their decarbonylated derivatives in deuterochloroform solution exist in the double chair conformation. The predominantly formed secondary alcohols isomers have preferred double chair conformation with the hydroxyl group equatorial relative to the plane of the piperidine ring. On the other hand, the epimeric alcohols have predominant boat-chair conformation; the piperidine ring takes the boat form due to intramolecular hydrogen bonding between the unshared electron pair of the nitrogen atom and hydroxyl group proton.Keywords: 7-alkoxyalkyl-3-thia-7-azabicyclo[3.3.1]non-9-one and its derivatives, conformational analysis, 1 H NMR spectra.The study of the three-dimensional structure of bicyclic compounds containing important biogenic elements such as oxygen, nitrogen, and sulfur holds interest not only in regard to the search for new physiologically active compounds but also for the development of conformational analysis and stereochemistry. We have described the synthesis of a series of 7-alkoxyalkyl-3-thia-7-azabicyclo[3.3.1]non-9-ones, their deoxygenated derivatives, and derived secondary alcohols [1]. In the present work, we have determined the three-dimensional structure of these compounds using high resolution 1 H NMR spectroscopy. We studied ketones 1-5 with various substituents at the nitrogen atom, their reduced analogs 6-10, and secondary alcohols 11-14. The chemical shifts and coupling constants for the individual stereoisomers isolated from alcohols 11 and 12 were used to interpret the rather complex spectra of alcohols 13 and 14, each of which is a mixture of two isomers that could not be separated.Bicyclo[3.3.1]nonanes and their 3,7-dihetero analogs exist in solution as one of four forms: double chair (cc), chair-boat (cb), boat-chair (bc), and double boat (bb) or as a mixture in conformational equilibrium [2]. The predominant configuration is determined not only by the overall electronic and steric factors within these __________________________________________________________________________________________

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.1]nonan-9-ones were synthesized by the double Mannich cyclization of tetrahydrothiopyran-4-one with suitable alkoxyalkylamines and paraformaldehyde in acetous methanol. Wolff-Kishner decarbonylation of these bicyclic ketones gave 7-alkoxyalkyl-3-thia-7azabicyclo[3.3.1]nonanes. The reduction of 7-alkoxyalkyl-3-thia-7-azabicyclo[3.3.1]nonan-9-ones by alkali metal hydride complexes leads to a mixture of two stereoisomeric secondary alcohols, which are epimers at C (9) . Active analgesic, antiarrhythmic, and antibacterial compounds were found among these products.

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