Carbon tetrabromide → Ethyl 3'-(bromomethyl)biphenyl-3-carboxylate

Participants

Reaction Steps

A mixture of ethyl-3-bromobenzoate (3.0 g, 13 mmol), [3-(hydroxymethyl)-phenyl]boronic acid (3.0 g, 20 mmol), PdCl2(PPh3)2 (0.46 g, 0.66 mmol), K2CO3 (3.6 g, 26 mmol), methanol (4 mL), and toluene (36 mL) was heated at 80° C. for 18 h under N2 and then allowed to cool to rt. The reaction mixture was filtered through Celite and then poured into a mixture of ethyl acetate and brine. The two layers were separated and the aqueous layer was extracted with ethyl acetate (×3). The organic extracts were dried (Na2SO4), filtered, concentrated and purified by silica gel chromatography to give ethyl 3′-(hydroxymethyl)biphenyl-3-carboxylate as an orange oil. A solution of CBr4 (5.8 g, 17 mmol) and CH2Cl2 (20 mL) was added dropwise to a solution of the above alcohol, PPh3 (4.6 g, 18 mmol), and CH2Cl2 (50 mL) at 0° C. under N2. The reaction was allowed to warm to rt, maintained for 2 h, concentrated, and purified by silica gel chromatography to give ethyl 3′-(bromomethyl)biphenyl-3-carboxylate as a clear oil. Ethyl 3′-(bromomethyl)biphenyl-3-carboxylate was used to alkylate 1-(2,2-dimethylpropyl)-4-propyl-1H-indol-5-ol following the procedure outlined in example 1. A mixture of the above indole (0.66 g, 1.4 mmol), 1 N LiOH (8 mL), and THF (8 mL) was heated at 40° C. for 2 d and then cooled to 0° C.—acetone can used in place of THF if faster reaction rates are desired. The reaction was acidified to pH=1 with conc. HCl and extracted with ethyl acetate (×3). The organic extracts were dried (Na2SO4), filtered, concentrated and purified by silica gel chromatography to give a yellow oil. 1H NMR (CDCl3, 500 MHz) δ 8.39 (s, 1H), 8.11 (d, 1H), 7.85 (d, 1H), 7.76 (s, 1H), 7.59-7.48 (m, 4H), 7.12 (d, 1H), 7.05 (d, 1H), 6.96 (d, 1H), 6.46 (d, 1H), 5.16 (s, 2H), 3.84 (s, 2H), 2.95 (t, 2H), 1.76 (m, 2H), 1.01 (t, 3H), 0.99 (s, 9H). MS (ESI): 456 (M+H).

Provenance & Evidence