2,3-Dichloro-5,6-dicyano-1,4-benzoquinone → HCID 68904099, compound

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Reaction Steps

A mixture of (R)-[(4R)-2,2-dimethyl-1,3-dioxolan-4-yl](2-thienyl)methanol and (S)-[(4R)-2,2-dimethyl-1,3-dioxolan-4-yl](2-thienyl)methanol (1.5 g, 7.0 mmol) was dissolved in tetrahydrofuran (28 mL) and sodium acetylide (2.1 g, 7.7 mmol; 18 wt % slurry in xylenes/light mineral oil) and the mixture was stirred for 2 hours. para-Toluenesulfonyl chloride (1.46 g, 7.7 mmol) was added, and stirring was continued for 2 hours, then indoline (2.5 g, 21 mmol) was added followed by 2,6-lutidine (0.81 mL, 7.0 mmol). After 72 hours the mixture was quenched with a saturated aqueous solution of ammonium chloride, diluted with ethyl acetate, washed with water, and saturated brine. The organic layer was separated, dried over anhydrous magnesium sulfate, filtered, and concentrated in vacuo. The crude product was purified via Isco chromatography (Redisep, silica, gradient 1-10% ethyl acetate in hexane) to afford 590 mg that was immediately dissolved in dioxane (10 mL) and treated with dichlorodicyanobenzoquinone (552 mg, 2.4 mmol) and stirred for 30 minutes. The mixture was diluted with ethyl acetate and washed with a saturated aqueous solution of sodium bicarbonate, water, and saturated brine. The organic layer was separated, dried over anhydrous magnesium sulfate, filtered, and concentrated in vacuo. The crude product was purified via Isco chromatography (Redisep, silica, gradient 1-20% ethyl acetate in hexane) to afford 160 mg of 1-[(R)-[(4S)-2,2-dimethyl-1,3-dioxolan-4-yl](2-thienyl)methyl]-1H-indole. HRMS: calcd for C18H19NO2S+H+, 314.12092; found (ESI-FTMS, [M+H]1+), 314.12089.

Provenance & Evidence