An Improved and Simple Route for the Synthesis of 3-Quinuclidinone Hydrochloride

An improved method for the synthesis of 3-quinuclidinone hydrochloride 4 from piperidine-4-carboxylic acid 1 has been described. Reaction of piperidine-4-carboxylic acid 1 with thionyl chloride and ethanol gave ethyl piperidine 4-carboxylate 2. It was further condensed with methyl chloroacetate in presence of sodium carbonate to give ethyl 1-(2-methoxy-2- oxoethyl)piperidine-4-carboxylate 3. One pot Dieckmann reaction of 3 in presence of potassium tertbutoxide followed by hydrolysis and decarboxylation gave title compound azabicyclo[2.2.2]oct-3-one hydrochloride 4. Keywords: 3-quinuclidinone hydrochloride, Dieckmann reaction, isonepecotic acid, Gram scale synthesis.