反应详情

15 g (40.4 mmol) of ethyltriphenylphosphonium bromide was placed in 60 ml of tetrahydrofuran and treated dropwise at -40° with 28 ml (45 mmol) of 1.6 molar butyllithium solution in n-hexane. The orange suspension obtained was stirred at -40° for a further 20 minutes and subsequently a solution of 10 g (36 mmol) of 7-chloro-5,6-dihydro-5-methyl-6-oxo-4H-imidazo[1,5-a][1,4]benzodiazepine-3-carboxaldehyde in 250 ml of tetrahydrofuran was added dropwise thereto within 50 minutes at -40° to -50°. The mixture was stirred at room temperature for a further 2 hours and subsequently filtered. The filtrate was evaporated and chromatographed on silica gel while eluting with cyclohexane/ether/isopropanol (3:3:1). There was obtained 7-chloro-4,5-dihydro-5-methyl-3-[(Z)-propenyl]-6H-imidazo[1,5-a][1,4]benzodiazepin-6-one of melting point 169.5°-170.5° (from ethyl acetate/hexane) and 7-chloro-4,5-dihydro-5-methyl-3-[(E)-propenyl]-6H-imidazo[1,5-a][1,4] benzodiazepin-6-one of melting point 200°-201° (from acetonitrile).

1. customThe orange suspension obtained
2. waitwithin 50 minutes at -40° to -50°
3. stirringThe mixture was stirred at room temperature for a further 2 hours
4. filtrationsubsequently filtered
5. customThe filtrate was evaporated
6. customchromatographed on silica gel
7. washwhile eluting with cyclohexane/ether/isopropanol (3:3:1)