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 the benzene sulfonate salt thereof, and compounds useful in that process

1. A 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 of formula (F)

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 which is a hypervalent iodine compound of formula (DM)

wherein R1 is acyl.

2. The process of claim 1 , wherein the compound of formula (EM) is 3-[(S)-7-bromo-2-((R)-2-hydroxy-propylamino)-5-pyridin-2-yl-3H benzo[e][1,4]diazepin-3-yl]-propionic acid methyl ester of formula (E)

3. A 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 benzene sulfonate (P) which comprises the steps of,

(a) 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 which is a hypervalent iodine compound of formula (DM)

wherein R1 is acyl, and

(b) treating the reaction product obtained in step (a) with benzene sulfonic acid in an organic solvent or an organic solvent mixture, to produce the compound (P), and optionally (c) isolating the compound (P).

4. The process of claim 3 , wherein the compound of formula (EM) is 3-[(S)-7-bromo-2-((R)-2-hydroxy-propylamino)-5-pyridin-2-yl-3H-benzo[e][1,4]diazepin-3-yl]-propionic acid methyl ester of formula (E)

5. The process of claim 3 , further comprising preparing 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) by a method comprising reacting a compound of formula (E1)

with (R)-1-amino-2-propanol or (S)-1-amino-2-propanol.

6. The process of claim 5 , characterized in that the compound of formula (E1) is reacted with (R)-1-amino-2-propanol.

7. The process of claim 3 , wherein 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) is crystallised from a solvent or a solvent mixture.

8. The process of claim 5 , further comprising preparing a compound of the formula (E1) by a method comprising reacting 3-[(S)-7-bromo-2-oxo-5-pyridin-2-yl-2,3-dihydro-1H-1,4-benzodiazepin-3-yl]propionic acid methyl ester of formula (D)

with lithium diisopropylamide (LDA) and bis-morpholinophosphorylchloridate (BMPC).

9. The process of claim 8 , further comprising the step of preparing 3-[(S)-7-bromo-2-oxo-5-pyridin-2-yl-2,3-dihydro-1H-1,4-benzodiazepin-3-yl]-propionic acid methyl ester of formula (D) by a method comprising cyclizing the compound of formula (C)

by the treatment with a base in an organic solvent or organic solvent mixture.

10. The process of claim 9 , further comprising the step of preparing the compound of formula (C) by cleaving the t Boc group from compound of formula (B)

by treatment with hydrogen chloride.

11. The process of claim 10 , further comprising the step of preparing the compound of formula (B) by treating (2-amino-5-bromo-phenyl)-pyridin-2-yl-methanone of formula (A)

with t Boc-Glu(OMe)-OH in presence of a coupling agent.

12. The process of claim 7 , wherein the solvent or solvent mixture is ethyl acetate, isobutylacetate, 2-propanol, toluene or ethyl acetate/heptane.

13. The process of claim 1 , wherein the hypervalent iodine compound of formula (DM) is 1,1, 1-triacetoxy-1, 1-dihydro-1,2-benzoiodoxol-3(1H)-one (Dess-Martin periodinane).

14. The process of claim 3 , wherein the hypervalent iodine compound of formula (DM) is 1,1, 1-triacetoxy-1,1-dihydro-1,2-benzoiodoxol-3(1H)-one (Dess-Martin periodinane).