Ammonium Chloride → tert-Butyl 5-ethenyl-1H-indole-1-carboxylate

Participants

Reaction Steps

To a suspension of methyltriphenylphosphonium bromide (8.1 g, 22.7 mmol) in THF (140 mL) at 0° C. was added nBuLi (1.6 M in hexanes, 14.2 mL, 22.7 mmol) dropwise over 10 min. After 20 min of stirring, a solution of the 5-formyl-indole-1-carboxylic acid tert-butyl ester (4.63 g, 14.8 mmol) in THF (20 mL) was introduced slowly over 20 min. The reaction was warmed slowly to room temperature, stirred 30 min. The reaction mixture was poured into saturated ammonium chloride and the separated aqueous phase was extracted with ethylacetate (3×100 mL). The combined organic phase was dried over sodium sulfate, filtered and concentrated. The residue was purified by chromatography (methylene chloride to 1% acetone-methylene chloride) to give 5-vinyl-indole-1-carboxylic acid tert-butyl ester (4.7 g, 100%) or similarly 6-vinyl-indole-1-carboxylic acid tert-butyl ester.

Provenance & Evidence