0.04 gram (0.36 millimole) of 4-dimethylaminopyridine, 0.94 gram (7.26 millimoles) of ethyl diisopropylamine, and 0.41 gram (3.63 millimoles) of glutaric anhydride were added successively to a solution of 1.00 gram (3.63 millimoles) of 4-(5H-dibenzo[a,d]cyclohepten-5-yl)-piperidine and the resulting mixture stirred at ambient temperature for two hours. The reaction mixture was diluted with 100 milliliters of methylene chloride and washed with aqueous hydrochloric acid and then with brine. The washed solution was dried over magnesium sulfate, the drying agent filtered and the solution evaporated in vacuo whereupon a foam was produced which when triturated with hot acetonitrile produced white crystals. The crystals were recrystallized from hot acetic acid/acetonitrile to obtain 4-(5H-dibenzo[a,d]cyclohepten-5-yl)-δ-oxo-1-piperidinepentanoic acid product, m.p. 180°-186° C. The product had elemental analyses as follows:
