Process for the preparation of a stilbene derivative having analgesic and anti-inflammatory properties

Stilbene derivatives having the formula where R1 and R2 are independently hydrogen or a lower alkyl, lower alkoxy, halo or haloalkyl group and R3 is hydrogen or a lower alkyl group, are prepared by hydrolysis of a compound represented by the general formula where M is -HC(R3)CN, -CH2C(S)B where B is the amino group or -HC(R3)COOA where A is an alkyl group, in water, an organic solvent or their mixture, in the presence of an acid or an alkali. The compounds thus prepared have excellent analgesic and anti-inflammatory activity and their toxicity is extremely low. In particular, 2-(3-stilbene)propionic acid is approximately 1.5 times more effective than ibuprofen, as regards the anti-inflammatory and analgesic activity and its oral LD50 value in mice is 2152 mg/kg, that is to say approximately two times more than in the case of ibuprofen.