Dichloromethane → (S)-2-(Benzhydrylidene-amino)-3-(3-bromo-4-fluoro-phenyl)-propionic acid tert-butyl ester

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Reaction Conditions

Reaction Steps

To a flame-dried flask was added (benzhydrylidene-amino)-acetic acid tert-butyl ester (250 mg, 0.846 mmol), O-allyl-N-(9-anthracenylmethyl)-cinchonidinium bromide (51 mg, 0.085 mmol), and DCM (5 mL). The flask was cooled to −55° C. and CsOH.H2O (1.4 g, 8.46 mmol) was added. The mixture was stirred for 30 min, treated with 3-bromo-4-fluorobenzyl bromide (1.1 g, 4.23 mmol), and stirred at −55° C. overnight. The mixture was diluted with Et2O (5 mL) and water (10 mL), warmed to rt, and washed with water and brine. The organic layer was dried (MgSO4) and concentrated. The residue was purified by column chromatography to provide the title compound (300 mg, 74%, er=97:3). MS (ESI+): mass calcd. for C26H25BrFNO2, 482.4; m/z found, 483.4 [M+H]+. 1H NMR (400 MHz, CDCl3): 7.59-7.54 (m, 2H), 7.41-7.20 (m, 7H), 7.02-6.91 (m, 2H), 6.72 (d, J=6.5 Hz, 2H), 4.11-4.07 (m, 1H), 3.19-3.08 (m, 2H), 1.45 (s, 9H).

Provenance & Evidence