NOVELTY - Preparing Prasugrel or its salt, involves: a) brominating 1-cyclopropyl-2-(2-fluoro-phenyl)-ethanone (V) with liquid bromine to obtain 2-bromo-1-cyclopropyl-2-(2-fluoro-phenyl)-ethanone (IV); b) condensing compound (IV) with hydrochloride salt of 5,6,7,7a-tetrahydro-4H-thieno(3,2-c)pyridin-2-one (III) to obtain 5-(2-cyclopropyl-1-(2-fluoro-phenyl)-2-oxo-ethyl)-5,6,7,7a-tetrahydro-4H-thieno(3,2-c)pyridin-2-one (II); c) acetylating compound (II) to obtain Prasugrel base (I); and optionally preparing their salts by d) converting Prasugrel base (I) with maleic acid, or into its salt.    USE - For preparing prasugrel base and its salt (claimed) used as a prophylactic or therapeutic agent for thrombosis or embolism.    ADVANTAGE - The process prepares prasugrel and maleate salt of prasugrel in high yields and purity, which can be used at industrial scale. The prasugrel maleate is obtained with purity higher than 99.5%. The maleate salt of prasugrel exhibits excellent oral absorption, metabolism into the active compound and activity in inhibition of platelet aggregation, low toxicity, and further excellent storage and handling stability. The process prepares Prasugrel and Prasugrel maleate or their salts in good yields and a high purity. The improved process is applicable at industrial scale and uses less toxic reactants and solvents and thus is more environmentally friendly.    DETAILED DESCRIPTION - Preparing Prasugrel and optionally its salt, involves: a) brominating 1-cyclopropyl-2-(2-fluoro-phenyl)-ethanone (V) with liquid bromine in the presence of a polar protic solvent to obtain 2-bromo-1-cyclopropyl-2-(2-fluoro-phenyl)-ethanone (IV); b) condensing the compound (IV) with hydrochloride salt of 5,6,7,7a-tetrahydro-4H-thieno(3,2-c)pyridin-2-one (III) in the presence of a base in a polar aprotic solvent to obtain 5-(2-cyclopropyl-1-(2-fluoro-phenyl)-2-oxo-ethyl)-5,6,7,7a-tetrahydro-4H-thieno(3,2-c)pyridin-2-one (II); c) acetylating the compound (II) in the presence of aprotic solvent, acetylating agent and catalyst to obtain Prasugrel base (I); and optionally preparing their salts by either: d) converting Prasugrel base (I) with maleic acid in the presence of a polar aprotic solvent into Prasugrel maleate (Ib), and optionally, purifying prasugrel maleate, obtaining prasugrel base and then converting prasugrel base into another salt; or e) converting Prasugrel base (I) into salt of prasugrel. An INDEPENDENT CLAIM is included for preparing the compound (IV) involving: brominating the compound (V) with liquid bromine in the presence of a polar protic solvent to obtain the compound (IV).