Process for preparing 3-[(45)-8-bromo-1-methyl-6-(2-pyridinyl)-4H-imidazo[1,2-A][1,4]benzodiazepine-4-yl]propionic acid methyl ester or the benzene sulfonate salt thereof, and compounds useful in that process

The invention concerns a new process for preparing 3-[(4S)-8-bromo-1-methyl-6-(2-pyridinyl)-4H-imidazo[1,2-a][1,4]benzodiazepine-4-yl]-propionic acid methyl ester or 3-[(4S)-8-bromo-1-methyl-6-(2-pyridinyl)-4H-imidazo[1,2-a][1,4]benzodiazepine-4-yl]propionic acid methyl ester benzene sulfonate (P) which comprises reacting 3-[(S)-7-bromo-2-((R and/or S)-2-hydroxy-propylamino)-5-pyridin-2-yl-3H-benzo[e][1,4]diazepin-3-yl]-propionic acid methyl ester of formula (EM) with an oxidizing agent and optionally treating the reaction product under acidic conditions, such as to produce the compound of formula (F) or the compound (P), and new compounds useful as starting material or as intermediate for performing that process.