Aluminium lithium hydride → (R)-3-((1-Methylpyrrolidin-2-yl)methyl)-5-vinyl-1H-indole

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Reaction Steps

A solution (R)-3-(N-Benzyloxycarbonylpyrrolidin-2-ylcarbonyl )-5-bromo-1H-indole (Example 5a, 252 mg, 0.59 mmol), tributyl(vinyl)tin (0.20 mL, 0.68 mmol) and tetrakistriphenyphosphine palladium (0) (84 mg, 0.073 mmol) in anhydrous DMF (3 mL) was stirred at 95-100° C. for 1 day. After cooling to room temperature, the product was taken into ethyl acetate, filtered through celite, washed with water (2×) and brine (1×), dried over sodium sulfate and the solvent was removed in vacuo. Flash chromatography on silica gel (60-100% ethyl acetate in hexanes) yielded (R)-5-vinyl-3-[(N-carbobenzyloxypyrrolidin-2-yl)carbonyl]-1H-indole (115 mg, 52%). A solution of LAH (0.77 mL, 1M in THF, 0.77 mmol) was added slowly to a cooled (0° C.) solution of (R)-5-vinyl-3-[(N-carbobenzyloxypyrrolidin-2-yl) carbonyl]-1H-indole (115 mg, 0.31 mmol) in THF (5 mL). Once the addition was completed, the reaction mixture was stirred at reflux for 2 h prior to quenching with sodium sulfate decahydrate. The product was taken into ethyl acetate, filtered to remove the solid residue, and the solvent was removed in vacuo. Flash chromatography on silica gel (5% 2M methanolic ammonia in dichloromethane) yielded (R)-5-vinyl-3-[(N-methylpyrrolidin-2-yl) methyl]-1H-indole (52 mg, 71%). HRMS-FAB+ for C16H20N2 : calculated MH+ :241.17047; found MH+ :241.17036.

Provenance & Evidence