[N:1]([CH:4]1[CH2:10][CH2:9][C:8]2[CH:11]=[CH:12][CH:13]=[CH:14][C:7]=2[NH:6][C:5]1=[O:15])=[N+:2]=[N-:3].CC(C)([O-])C.[K+].Br[CH2:23][C:24]([O:26][CH2:27][CH3:28])=[O:25]>O1CCCC1>[N:1]([CH:4]1[CH2:10][CH2:9][C:8]2[CH:11]=[CH:12][CH:13]=[CH:14][C:7]=2[N:6]([CH2:23][C:24]([O:26][CH2:27][CH3:28])=[O:25])[C:5]1=[O:15])=[N+:2]=[N-:3]3-azido-2,3,4,5-tetrahydro-1H[1]benzazepin-2-one (see example 1, 5.0 kg) was added portionwise under nitrogen to potassium tert-butoxide (3.03 kg) in dry tetrahydrofuran (50 liters) at such a rate that the temperature is is maintained below 5°, and the reaction mixture was stirred for 1 hour after the addition is completed. A solution of ethyl bromoacetate (4.38 kg) in tetrahydrofuran (5 liters) was then added slowly so as to maintain the temperature below 5°. The reaction mixture was then stored at room temperature overnight. Filteraid (1.5 kg of Hiflo) was added, and the reaction mixture was filtered. The filter cake was washed with tetrahydrofuran and the combined tetrahydrofuran solution was evaporated to dryness to give 3-azido-1-ethoxycarbonylmethyl-2,3,4,5-tetrahydro-1H-[1]-benzazepin-2-one which is used without further purification in the next step.
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