Doxergan,Specia,France,1964
The development of oxomemazine is the result of a systematic exploration of phenothiazine compounds in the mid-20th century. Following the significant sedative effects of the first-generation antihistamine promethazine, scientists focused on optimizing its pharmacological properties through structural modification. In the late 1950s and early 1960s, researchers synthesized oxomemazine by chemically modifying the side chains of promethazine. This new compound retained potent antihistamine activity while enhancing its antitussive and sedative effects. Based on these properties, oxomemazine was marketed as an antitussive in the 1960s, often under the brand name Toplexil®, and was particularly suitable for treating allergic dry cough accompanied by sleep disturbances.
(±)-Oxomemazine, is a phenothiazine-type antihistamines, that has also shown antibacterial activity against Mycobacterium tuberculosis.
ChEBI: Oxomemazine is a member of phenothiazines.
Phenothiazine is reacted with 3-dimethylamino-2-methylpropyl chloride in the presence of sodium amide to give 3-(10-phenthiazinyl)-2-methyl-1dimethylaminopropane. 11.9 g of of this intermediate is dissolved with agitation in glacial acetic acid (120 cc). Pure sulfuric acid (d = 1.83; 0.5 cc) is added and a mixture of glacial acetic acid (10 cc) and hydrogen peroxide (8.5 cc of a solution containing 38 g of hydrogen peroxide in 100 cc) is then run in over 20 minutes. The temperature rises from 25°C to 35°C and is then kept at 60°C for 18 hours. The mixture is cooled and water (150 cc) is added and, with cooling, aqueous sodium hydroxide (d = 1.33; 220 cc). The resulting
mixture is extracted with ethyl acetate (3 x 100 cc), the solvent is evaporated on a water bath and the residue is recrystallized from heptane (150 cc). 3(9,9-dioxy-10-phenthiazinyl)-2-methyl-1-dimethylaminopropane (78 g) is obtained, MP 115°C.
The corresponding hydrochloride prepared in ethyl acetate and recrystallized from a mixture of ethanol and isopropanol melts at 250°C.
