Preparation process of an agonist of the thrombopoietin receptor

摘要

It relates to a preparation process of 2'-(benzyloxy)-3'-nitro-1,1'-biphenyl-3-carboxylic acid or a salt thereof comprising reacting 2-(benzyloxy)-1-bromo-3-nitrobenzene with a either 3-carboxyphenylboronic acid or a salt thereof or a (C 1 -C 4 )-alkyl ester thereof in the presence of Pd(OAc) 2 , tricyclohexylphosphine, a base, an appropriate solvent, and at an appropriate temperature; if appropriate, submitting the compound thus obtained to a hydrolysis reaction; and isolating the compound thus obtained in form of a salt of compound of formula (VI) or in form of the free acid by adding an acid. It also comprises the further preparation to eltrombopag or its salts from the new intermediate thus obtained by subsequent reduction of the nitro group and deprotection of the phenol, conversion of the amine intermediate obtained in a diazonium derivative, and either (1) subsequent reaction with ethyl acetoacetate and with (3,4-dimethylphenyl)hydrazine or a salt thereof, occurring the pyrazole ring formation by intermolecular cyclization, or (2) introduction of the pyrazole ring by reaction with 1-(3,4-dimethylphenyl)-3-methyl-3-pyrazolin-5-one.