Methyl Anthranilate → 2-(2-aminophenyl)propan-2-ol

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Reaction Steps

Thus, for example, 4,4-dimethyl-6-isonicotinoylamino-7-nitro-4H-3,1-benzoxazin-2-one is obtained by reacting methyl anthranilate with methyl magnesium iodide in ethereal solution to obtain o-aminophenyl-dimethylcarbinol, which is cyclised by reacting with phosgene in a mixture of toluene and chloroform as solvent in the presence of solid potassium carbonate to obtain 4,4-dimethyl-4H-3,1-benzoxazin-2-one. By subsequent nitration with fuming nitric acid (d=1.52), 4,4-dimethyl-6-nitro-benzoxazin-2-one is obtained which is converted by catalytic hydrogenation in the presence of Raney nickel in dimethyl formamide into 6-amino-4,4-dimethyl-4H-3,1-benzoxazin-2-one. By inserting an acetyl protecting group by means of acetic anhydride, the precondition for further nitration with fuming nitric acid (d=1.52) is created in the 7- position of the molecule. The acetyl protecting group is split off again from the resulting 6-acetamido-4,4-dimethyl-7-nitro-4H-3,1-benzoxazin-2-on e by treating with concentrated hydrochloric acid in isopropanol, and the resulting 6-amino-4,4-dimethyl-7-nitro-4H-3,1-benzoxazin-2-one is converted into 4,4-dimethyl-6-isonicotinoylamido-7-nitro-4H-3,1-benzoxazin-2-one by treating with isonicotic acid chloride in pyridine as solvent.

Provenance & Evidence