Sulfuric Acid → 11-Acetamido-2,3,4,5-tetrahydro-11-phenyl-11H-[1,3]diazepino[1,2-a]indole

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Reaction Steps

A suspension of 2,4,5,11-tetrahydro-11-phenyl-3H-[1,3]diazepino[1,2-a]indol-11-ol hydrobromide (2.89 g)in acetonitrile (16 ml) and methanesulphonic acid (100 drops) was added dropwise over 10 min to stirred sulphuric acid 98% w/w (8 ml) at 50°-60°. After 1/2 hour, the solution was cooled to room temperature, poured into water (200 ml), basified with sodium hyroxide (10 g) and sodium carbonate and extracted with chloroform (2×200 ml). The extracts were dried (MgSO4) and evaporated in vacuo. The brown oil was purified by chromatography (Al2O3 ; ethyl acetate) to give the product free base (0.82 g) as a colourless solid. The hydrochloride was prepared from ether-methanol as a solid (1.06 g), m.p. 285°-290° (dec.).

Provenance & Evidence