[CH3:1][C:2]1[C:7]2[NH:8][C:9](=[O:17])[C:10]3[CH:16]=[CH:15][CH:14]=[N:13][C:11]=3[NH:12][C:6]=2[CH:5]=[CH:4][CH:3]=1.CN(C=O)C.[H-].[Na+].[H][H].[CH2:27](I)[CH3:28]>>[CH2:27]([N:8]1[C:7]2[C:2]([CH3:1])=[CH:3][CH:4]=[CH:5][C:6]=2[NH:12][C:11]2[N:13]=[CH:14][CH:15]=[CH:16][C:10]=2[C:9]1=[O:17])[CH3:28]To a stirred suspension of 1.1 g (5 mmol) 6,11-dihydro-7-methyl-5H-pyrido-[2,3-b][1,5]benzodiazepin-5-one in 20 ml of dry DMF 0.13 g (5.5 mmol) of sodium hydride was added portionwise at room temperature. Once the evolution of hydrogen had ceased, the mixture was heated to 60° C. for 2 h, cooled to 10° C., and then 0.86 g (5.5 mmol) of ethyl iodide was added. The reaction mixture was stirred at room temperature overnight and then concentrated. The residue was poured into water, the solid collected, washed, dried and column chromatographed on 60 g of dry silica gel. The product (second fraction) was eluted with methylene chloride and methylene chloride/methanol 99/1 to give 0.6 g (80% of theory) of 6,11-Dihydro-6-ethyl-7-methyl-5H-pyrido[2,3-b][1,5]benzodiazepin-5-one m.p. 186°-188° C.
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