alphaprodine

Originator

Nisentil ,Roche ,US ,1949

Manufacturing Process

In a round-bottom flask provided with stirrer, dropping funnel, condenser and a gas outlet for keeping the system under nitrogen, 200 cc of dry ether is placed and 4.6 grams of lithium cut into thin strips is added. 52 grams of bromobenzene in 50 cc of dry ether are added dropwise and after addition, the mixture is refluxed for 2 hours. This procedure results in the formation of phenyl-lithium. Other aryl-lithium compounds can be prepared in a similar manner by reacting lithium metal or a lithium compound capable of transferring lithium and a compound having an exchangeable halogen group as, for example, bromonaphthalene.
The solution of phenyl-lithium is cooled to -20°C and to this a solution of 12.7 grams of 1,3-dimethyl-4-piperidone, prepared according to the method of Howton, J. Org. Chem. 10, 277 (1945), in ether is added dropwise with stirring. After the addition, the stirring is continued for a further 2 hours at - 20°C. The lithium complex, 1,3-dimethyl-4-phenyl-4-oxylithium piperidine, which forms is soluble in the ether and can be recovered there from. To prepare the piperidinol, the lithium complex, while in the reaction mixture is decomposed by the addition of an ice and hydrochloric acid mixture. The acidified layer is separated, basified and extracted with ether. After drying the ether solution and removing the solvent, the residue on distillation in vacuum distills chiefly at 155°C/10 mm, yielding the product, 1,3-dimethyl-4-phenyl- 4-hydroxypiperidine, which, on crystallization from n-hexane melts at 102°C. On treatment with propionic anhydride catalyzed with a trace of sulfuric acid,1,3-dimethyl-4-propionoxy-4-phenylpiperidine is attained. The latter compound can be converted into the hydrochloride salt by reaction with hydrogen chloride. This salt after crystallization from acetone has a melting point of 209°C.

brand name

Nisentil (Hoffmann-LaRoche).

Therapeutic Function

Narcotic analgesic