3614-69-5

White or almost white, crystalline powder.

Antihistaminic.

Forhistal Maleate (Ciba-Geigy).

Fenistil,Zyma,W. Germany,1961

ChEBI: Dimetindene maleate is an indene.

26 grams of 2-ethylpyridine is added dropwise with cooling to 20°C and in an atmosphere of nitrogen to a stirred solution of 650 ml of an 0.37 molar solution of phenyl lithium in benzene. After two hours a solution of 10 grams of 2-(2-dimethylaminoethyl)-indan-1-one in 50 ml of dry ether is added over a period of five minutes while stirring and cooling to room temperature. After standing for 24 hours the organo-lithium compounds are decomposed by the addition of 50 ml of water with external cooling. After separating the water phase from the organic solution, the latter is washed several times with 50 ml of water, and then extracted with a mixture of 40 ml of concentrated hydrochloric acid and 100 ml of water.
The acidic solution, containing the 2-(2-dimethylaminoethyl)-1-[1-(2-pyridyl)- ethyl]-indan-1-ol is heated on the steam bath for thirty minutes to effect dehydration to the desired indene derivative. The solution is cooled, made strongly basic with an aqueous solution of ammonia and then extracted with ether. The ether phase is dried over sodium sulfate, filtered, evaporated and the residue distilled.
At 15 mm pressure the excess of 2-ethylpyridine is removed, at 120°C/0.5 mm some unreacted 2-(2-dimethylaminoethyl)-indene distills and at 165°- 175°C/0.5 mm the 2-(2-dimethylaminoethyl)-3-[1-(2-pyridyl)-ethyl]-indene is collected. It may be converted to an aqueous solution of the dihydrochloride by dissolving it in the appropriate amount of dilute hydrochloric acid.
To a solution of 1.0 gram of 2-(2-dimethylaminoethyl)-3[1-(2-pyridyl)-ethyl]- indene in 10 ml of ethanol is added while stirring and heating 0.4 gram of maleic acid. On cooling the 2-(2-dimethylaminoethyl)-3-[1-(2-pyridyl)-ethyl]- indene maleate crystallizes, is filtered off, washed with a small amount of ethanol and recrystallized from ethanol, MP 158°C.

Antihistaminic

Dimethindene maleate, (±)2-[1-[2-[2-dimethylamino)ethyl]-inden-3-yl]ethyl]pyridinebimaleate (1:1) (Forhistal Maleate), is a white to off-whitecrystalline powder that has a characteristic odor and is sparinglysoluble in water. This potent antihistaminic agent may beconsidered a derivative of the unsaturated propylamines. Theprincipal side effect is some sedation or drowsiness. The antihistaminicactivity resides mainly in the levorotatory isomer.