Process for preparing trityl olmesartan medoxomil and olmesartan medoxomil

A process for the preparation of olmesartan medoxomil of formula (I):

• comprising (a) condensing 4-(1-hydroxy-1-methylethyl)-2-propyl-imidazol-5-carboxylic acid alkyl ester of formula (II):
• wherein R is C1-C6 alkyl with trityl biphenyl bromide of formula (III):
• in the presence of a polar aprotic solvent and a base selected from the group consisting of alkali metal carbonates, alkali metal hydroxides, alkali metal alkoxides, and tertiary amines to obtain a compound of formula (V),
• (b) deesterifying the compound of formula (V) with a base;
• (c) reacting the product of step (b) with 4-halomethyl-5-methyl-2-oxo-1,3-dioxolene of formula (IV),
• wherein X is halogen selected from F or Cl or Br or I, to obtain trityl olmesartan medoxomil of formula (VI);
• and (d) deprotecting the trityl olmesartan medoxomil (VI) to yield olmesartan medoxomil of formula (I),
• wherein the products of steps (a) and (b) are not isolated and steps (a), (b) and (c) are carried out in a single reaction vessel.