Methyl Isocyanate → 6-Methoxy-2-methyl-1H-indol-3-carboxylic acid methylamide

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Reaction Steps

To a stirred solution of 6-methoxy-2-methyl-1H-indole (500 mg, 3.1 mmol) (prepared according to JACS 1988, 110, 2242) in 8 mL anhydrous THF maintained at room temperature was added methylmagnesium bromide (1.13 ml, 3.0 M solution in diethyl ether, 3.41 mmol). After stirring for 1 hour at room temperature, a solution of 0.5M zinc chloride in THF (7.44 ml, 3.72 mmol) was introduced and the mixture was stirred for 1 hour at room temperature before addition of methyl isocyanate (424 mg, 7.44 mmol). The resulting mixture was stirred at ambient temperature overnight, quenched with water, and extracted with EtOAc. The combined organic layer was washed with brine, dried over Na2SO4, filtered and concentrated. The residue was purified by flash column chromatography eluting with 2–5% MeOH in CH2Cl2 to give 200 mg product (30% yield). 1H NMR (300 MHz, CD3OD) δ 7.55 (1H, d, J=8.6 Hz), 6.78 (1H, d, J=2.2 Hz), 6.70 (1H, dd, J=2.2, 8.6 Hz), 3.73 (3H, s), 2.90 (3H, s), 2.52 (3H, s). LCMS (ESI+) [M+H]/z Calc'd 219. found 219.

Provenance & Evidence