A process for the preparation of 5-[2-cyclopropyl-1-(2-fluorophenyl)-2-oxoethyl]-4,5,6,7-tetrahydrothieno[3,2-c]pyridine-2-yl acetate (prasugrel) of Formula (I) including the following steps: a) (2-fluorophenyl)-acetic acid of Formula (VI) is reacted in the presence of a base with cyclopropane carboxylic acid ethyl ester of Formula (VII), b) then the obtained 1-cyclopropyl-2-(2-fluorophenyl)ethanone of Formula (V) is brominated to obtain 2-bromo-1-cyclopropyl-2-(2-fluorophenyl)ethanone base of Formula (III), c) N-trityl-4,5,6,7-tetrahydrothieno[2,3-c]pyridine of Formula (VIII) is reacted with hexyllithium, then tributyl-borate, finally with hydrogen-peroxide, to form 5,6,7,7a-tetrahydrothieno[3,2-c]pyridine-2 -one hydrochloride of Formula (IV), d) the 2-bromo-1-cyclopropyl-2-(2-fluorophenyl)ethanone base of Formula (III) in the presence of sodium carbonate is reacted with 5,6,7,7a-tetrahydrothieno[3,2- c ]pyridine-2(4 H )-one hydrochloride of Formula (IV), to obtain the 5-[α-cyclopropyl carbonyl-2-fluorobenzyl)-2-oxo-2,4,5,6,7,7a-hexahydro-thieno[3,2-c]pyridine of Formula (II), e) the compound of Formula (II) is acetylated and the so obtained crude 5-[2-cyclo-propyl-1-(2-fluorophenyl)-2-oxoethyl]-4,5,6,7-tetrahydrothieno[3,2-c]pyridine-2-yl acetate (prasugrel) of Formula (I) is prepared, f) finally in a purification step the crude prasugrel is converted into a purified prasugrel product by removing a bromopentyl impurity of Formula (X) from 5-[2-cyclopropyl-1-(2-fluorophenyl)-2-oxoethyl]-4,5,6,7-tetrahydrothieno[3,2-c]-pyridine-2-yl acetate (prasugrel) of Formula (I) wherein said impurity is converted to an easily removable high-polarity quaternary ammonium iodide of formula (Xb) and wherein the use of ether solvents are excluded from each step of the process. a) (2-fluorophenyl)-acetic acid of Formula (VI) is reacted in the presence of a base with cyclopropane carboxylic acid ethyl ester of Formula (VII), b) then the obtained 1-cyclopropyl-2-(2-fluorophenyl)ethanone of Formula (V) is brominated to obtain 2-bromo-1-cyclopropyl-2-(2-fluorophenyl)ethanone base of Formula (III), c) N-trityl-4,5,6,7-tetrahydrothieno[2,3-c]pyridine of Formula (VIII) is reacted with hexyllithium, then tributyl-borate, finally with hydrogen-peroxide, to form 5,6,7,7a-tetrahydrothieno[3,2-c]pyridine-2 -one hydrochloride of Formula (IV), d) the 2-bromo-1-cyclopropyl-2-(2-fluorophenyl)ethanone base of Formula (III) in the presence of sodium carbonate is reacted with 5,6,7,7a-tetrahydrothieno[3,2- c ]pyridine-2(4 H )-one hydrochloride of Formula (IV), to obtain the 5-[α-cyclopropyl carbonyl-2-fluorobenzyl)-2-oxo-2,4,5,6,7,7a-hexahydro-thieno[3,2-c]pyridine of Formula (II), e) the compound of Formula (II) is acetylated and the so obtained crude 5-[2-cyclo-propyl-1-(2-fluorophenyl)-2-oxoethyl]-4,5,6,7-tetrahydrothieno[3,2-c]pyridine-2-yl acetate (prasugrel) of Formula (I) is prepared, f) finally in a purification step the crude prasugrel is converted into a purified prasugrel product by removing a bromopentyl impurity of Formula (X) from 5-[2-cyclopropyl-1-(2-fluorophenyl)-2-oxoethyl]-4,5,6,7-tetrahydrothieno[3,2-c]-pyridine-2-yl acetate (prasugrel) of Formula (I) wherein said impurity is converted to an easily removable high-polarity quaternary ammonium iodide of formula (Xb) and wherein the use of ether solvents are excluded from each step of the process. <EOS>