Iodoethane → 4,5-dihydro-3-(1-hydroxypropyl)-5-methyl-6H-imidazo[1,5-a][1,4]benzodiazepin-6-one

Beteiligte Stoffe

Reaktionsschritte

1.22 g (50.2 mmol) of magnesium shavings are covered with 60 ml of absolute diethyl ether under an argon atmosphere and treated with 2-3 drops of ethyl iodide. When the Grignard reaction starts, a solution of 4.3 ml (51 mmol) of ethyl iodide in 10 ml of absolute diethyl ether is added dropwise at the boiling point. After the magnesium has dissolved completely, the mixture is treated dropwise with a solution, warmed to 30° C., of 0.65 g (40 mmol) of 5,6-dihydro-5-methyl-6-oxo-4H-imidazo[1,5-a][1,4]benzodiazepine-3-carboxaldehyde in 200 ml of absolute tetrahydrofuran. The yellow coloured suspension is heated to boiling under reflux for ca 5.5 hours, cooled to room temperature and poured into 600 ml of ice/water. The mixture is filtered over Dicalit while rinsing with tetrahydrofuran. After concentration of the filtrate in vacuo, the residue is taken up in 250 ml of chloroform. The chloroform phase is washed twice with 60 ml of water each time, dried over magnesium sulphate and concentrated. The crude product is chromatographed on silica gel using chloroform/methanol (19:1, vol/vol) for the elution. Afte recrystallisation from ca 40 ml of ethyl acetate, there is obtained 4,5-dihydro-3-(1-hydroxypropyl)-5-methyl-6H-imidazo[1,5-a][1,4]benzodiazepin-6-one of melting point 145°-147° C.

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