Disclosed is a process for the synthesis of ivabradine of formula (I), characterised in that the compound of formula (VI) is subjected to a lactamisation reaction, in the presence of a coupling agent (such as oxalyl chloride, thionyl chloride, N,N-dicyclohexylcarbodiimide (DCC), 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDCI), N,N-carbonyldiimidazole (CDI), 1-propanephosphonic acid cyclic anhydride (T3P) and 1-(methylsulphonyl)-1Hbenzotriazole) and a base (such as triethylamine, diisopropylethylamine and pyridine), in an organic solvent (such as dichloromethane, tetrahydrofuran, acetonitrile, acetone and toluene), to yield ivabradine of formula (I), which may be converted into addition salts thereof with a pharmaceutically acceptable acid selected from hydrochloric acid, hydrobromic acid, sulphuric acid, phosphoric acid, acetic acid, trifluoroacetic acid, lactic acid, pyruvic acid, malonic acid, succinic acid, glutaric acid, fumaric acid, tartaric acid, maleic acid, citric acid, ascorbic acid, oxalic acid, methanesulphonic acid, benzenesulphonic acid and camphoric acid and into hydrates thereof. Also disclosed are synthetic intermediates selected from { 2-[2-({ 3[{ [(7S)-3,4-dimethoxybicyclo [4.2.0]octa-1,3,5-trien-7-yl]methyl} (methyl)-amino]propyl} amino)ethyl]-4,5-dimethoxyphenyl} acetic acid, { 2-[2-({ 3-[{ [(7S)-3,4-dimethoxybicyclo[4.2.0]octa-1,3,5-trien-7-yl]methyl} (methyl)-amino]propyl} amino)ethyl]-4,5-dimethoxyphenyl} acetonitrile, (2-{ 2-[(3-chloropropyl)amino]ethyl} -4,5-dimethoxypheny)acetonitrile, Ethyl N-{ 2-[2-(cyanomethyl)-4,5-dimethoxyphenyl]ethyl} -ß-alaninate oxalate, (2-{ 2-[(3-hydroxypropyl)amino]ethyl} -4,5-dimethoxyphenyl)acetonitrile and 3-[{ [(7S)-3,4-dimethoxybicyclo[4.2.0]octa-1,3,5-trien-7-yl]methyl} (methy)amino]-1-propanol.
