The solution of 8.0 g of 1-methyl-3-acetonyl-4-(3-methoxyphenyl)-1,5,6,7-tetrahydro-2H-azepinone, 14.2 g of piperidine, 6.4 ml of 5 N methanolic hydrogen chloride and 1.91 g of sodium cyanoborohydride in 100 ml of methanol is refluxed overnight. An additional portion of 1.91 g of sodium cyanoborohydride is added and refluxing continued for another day. The solution is cooled, acidified with a 35 ml of concentrated hydrochloric acid and evaporated. The residue is diluted with 100 ml of water, the aqueous solution washed with benzene, filtered, basified with 65 ml 3 N aqueous sodium hydroxide and extracted with diethyl ether. The extract is dried, evaporated and the residue crystallized from petroleum ether and recrystallized from hexane, to yield the 1-methyl-3-(2-piperidinopropyl)-4-(3-methoxyphenyl)-1,5,6,7-tetrahydro-2H-azepinone melting at 101°-103°.
