2-Methyl-2-butene → HCID 67372252, compound

Participants

Reaction Steps

To a vigorously stirred solution of 2-chloro-1-phenyl-1H-indole-3-carboxaldehyde (4.0 g, 15.6 mmol), 2 M 2-methyl-2-butene (74 mL, 148 mmol) in dioxane (58 mL) at 25° C. is added dropwise over 30 min a solution of sodium chlorite (7.8 g, 86 mmol) and sodium dihydrogenphosphate hydrate (7.8 g, 56 mmol) in water (40 mL). After 2.5 hr, more sodium chlorite (1.92 g, 21.2 mmol) and sodium dihydrogenphosphate hydrate (1.92 g) are added. After 2.5 hr, more sodium chlorite (0.96 g, 10.6 mmol) and sodium dihydrogenphosphate hydrate (0.96 g) are added. After a total reaction time of 6.5 hr, ethyl acetate (100 mL) is added and stirring continued for 45 min. The aqueous layer is separated and extracted with ethyl acetate (2×60 mL). The combined ethyl acetate layer and extracts is concentrated to approximately 80 mL and then extracted with 1% aq. sodium hydroxide (3×150 mL). The combined aqueous extract is made acidic with conc. hydrochloric acid. The resulting solids are collected by filtration, washed with water and crystallized from 2-propanol to afford 2-chloro-1-phenyl-1H-indole-2-carboxylic acid (3.28 g, 77.5% yield) as a pale yellow solid. NMR (CDCl3) 8.30 (1H, d), 7.60 (3H, m), 7.41 (2H, d), 7.38 (1H, t), 7.23 (1H, m), 7.10 (1H, d).

Provenance & Evidence