Pyrrolo[2,1-C][1,4]benzodiazepine hybrids and a process for the preparation thereof

A process for the preparation of a compound of formula 5:

• wherein R is selected from the group consisting of H, Cl, F and CH3;
• and n=1, 2 or 3, said process comprising the steps of:
• a) reacting (2S)-N-(4-hydroxy-3 -methoxy-2-nitrobenzoyl)pyrrolidine-2-carboxaldehyde diethyl thioacetal of formula 2
• with 1-(3 -bromo alkyl)-6-R-4-phenyl-1,2-dihydro-2-quinazolinone of formula 1,
• wherein R is selected from the group consisting of H, Cl, F and CH3 and n=1, 2 or 3, in an aprotic water miscible organic solvent,
• in the presence of anhydrous mild inorganic base, under refluxing temperature in an oil bath, for a period of about 48 hrs, followed by the removal of inorganic base by filtration and evaporating the organic solvent to obtain the resultant crude product and purifying it by known method to obtain the desired product of 2S-N-{4-[3-(6-R-4-phenyl- 1,2-dihydro-2-quinazolinone)]alkyl]oxy-5-methoxy-2-nitrobenzoyl}pyrrolidine-2-carboxaldehyde diethyl thioacetal of formula 3, wherein n=1, 2 or 3
• b) reducing 2S-N-{4-[3-(6-R-4-phenyl-1,2-dihydro-2-quinazolinone)]alkyl]oxy-5-methoxy-2-nitrobenzoyl }pyrrolidine-2-carboxaldehyde diethyl thioacetal of formula 3 with anhydrous tin chloride, in an alcohol, under reflux, followed by the evaporation of alcohol and adjusting the pH of the resultant product layer to about 8 by using a base, followed by extraction with ethyl acetate and washing the combined organic phase with brine solution and evaporating the solvent to obtain the desired 2S-N- {4-[3 -(6-chloro-4-phenyl- 1,2-dihydro-2-quinazolinone)]alkyl]oxy-5-methoxy-2-aminobenzoyl}pyrrolidine -2-carboxaldehyde diethyl thioacetal of formula formula 4, wherein R is selected from the group consisting of H, Cl, F and CH3and n=1, 2 or 3,
• c) reacting 2S-N- {4-[3-(6-chloro-4-phenyl-1,2-dihydro-2-quinazolinone)]alkyl]oxy-5-methoxy-2-aminobenzoyl }pyrrolidine-2-carboxaldehyde diethylthioacctal of formula 4 with mercurous chloride, in a mixture of water and organic solvent, in the presence of mild inorganic, under stirring, at a temperature of about 20-30° C., for a period of 8-12 hrs, followed by the extraction of yellow organic supernatant and washing with sodium bi carbonate and brine, respectively, and evaporating the organic layer, under reduced pressure to obtain the desired product of formula 5.