3-Phenoxybenzoic acid → (+/-)-2-(3-Phenoxybenzoyl)-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid ethyl ester

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Reaction Steps

To a stirred solution of (±)-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid ethyl ester (6.26 g, 30.5 mmol) and 3-phenoxybenzoic acid (7.19 g, 33.6 mmol) in chloroform (150 mL) was added 1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide hydrochloride (6.43 g, 33.5 mmol). The reaction was allowed to proceed overnight and then washed with aqueous sodium bicarbonate solution, dried (sodium sulfate) and concentrated. The crude product was purified by flash chromatography over silica (hexanes/ethyl acetate) to afford 12.07 g (99%) of product as a colorless gum. In chloroform-d solvent, the proton NMR spectra of this compound appears as a 55:45 mixture of rotamers: 1H NMR (CDCl3) δ 7.46-6.90 (m, 13H), 5.46 (t, J=5.6 Hz, 0.55H), 5.18 (d, J=17.6 Hz, 0.45H), 4.80-4.73 (m, 0.45H), 4.68-4.50 (m, 1.55H), 4.22-4.07 (m, 1.10H), 4.05-3.92 (m, 0.90H), 3.34-3.19 (m, 1.55H), 3.16-3.06 (m, 0.45H), 1.19 (t, J=7.1 Hz, 1.65H), 1.04 (t, J=7.1 Hz, 1.35H) ppm.

Provenance & Evidence