Process for the preparation of 5,6,7,7a-4H-tetrahydrothieno (3,2-c)pyridin-2-one derivatives.

摘要

Process for the preparation of derivatives of formula: <IMAGE> in which R denotes hydrogen or a phenyl radical optionally substituted by at least one halogen atom or a lower alkyl, lower alkoxy, nitro, carboxy, alkoxycarbonyl or cyano group; R' denotes hydrogen or a lower alkyl group, and n is zero or an integer from 1 to 4 and their addition salts with inorganic or organic acids, the process being characterised in that: a) a compound of formula II: <IMAGE> in which R, R' and n are as defined above, in solution in a mixture of acetic acid and hydrobromic acid is treated with a solution of aqueous hydrogen peroxide; b) the bromo derivative obtained at the outcome of stage a) and having the formula III: <IMAGE> is converted into an organomagnesium derivative in an anhydrous inert solvent and the organomagnesium derivative obtained is then condensed with t-butyl perbenzoate to obtain the compound of formula IV: <IMAGE> c) the compound of formula IV obtained above is converted into a compound of formula I by heating to temperatures of between 80 and 180 DEG C in the presence of an inorganic or organic acid.