Benzyl Bromide → 1-benzyl-5-chloro-1H-pyrrolo[3,2-b]pyridine-2-carbaldehyde

Participants

Reaction Steps

K2CO3 (0.39 g, 2.8 mmol) and benzyl bromide (0.12 mL, 1.0 mmol) were added to a solution of 5-chloro-1H-pyrrolo[3,2-b]pyridine-2-carbaldehyde (0.17 g, 0.94 mmol, from Step 1) in DMF (3.6 mL). After 15 minutes, the reaction mixture was partitioned between EtOAc and water, and the organic layer was washed with two portions of water, one portion of brine, then dried over sodium sulfate, filtered and concentrated to afford 0.26 g of crude 1-benzyl-5-chloro-1H-pyrrolo[3,2-b]pyridine-2-carbaldehyde as a yellow solid. Sodium tetrahydroborate (53 mg, 1.4 mmol) was added to a solution of the crude aldehyde in THF (5.0 mL) and EtOH (5.0 mL). After 15 minutes, the reaction mixture was quenched with saturated NH4Cl, and was extracted with EtOAc. The extracts were washed with water followed by brine, dried over sodium sulfate, filtered and concentrated. Flash chromatography, eluting with a gradient from 0-40% EtOAc in hexanes afforded purified product as a white solid (0.21 g, 82%). 1H NMR (300 MHz, CDCl3) δ 7.45 (d, J=8.6 Hz, 1H), 7.33-7.25 (m, 3H), 7.06 (d, J=8.6 Hz, 1H), 7.03-6.88 (m, 2H), 6.66 (s, 1H), 5.47 (s, 2H), 4.78 (s, 2H).

Provenance & Evidence