Ammonia → 6-acetamido-trans-4-amino-3,4-dihydro-2,2-dimethyl-7-nitro-2H-benzo[b]pyran-3-ol

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Reaction Steps

6-Acetamido-3,4-epoxy-3,4-dihydro-2,2-dimethyl-7-nitro-2H-benzo[b]pyran (1.0 g, the preparation of which is described in European Pat. No. 28,064) was dissolved in dry ethanol (150 ml) and saturated with ammonia during 3 h, with cooling. The reaction mixture was stirred at room temperature for 5 days and evaporated. The crude residue was purified on the chromatotron (80% ethyl acetate-pentane to 20% methanol-ethyl acetate gradient elution), to give the title compound (410 mgm). A small portion was converted to the hydrochloride salt and recrystallised from ethanol-diethyl ether, with m.p. 258°-261° C.

Provenance & Evidence