Oxygen → (3R,4R)-1-Benzyl-4-(4-chloro-phenyl)-pyrrolidine-3-carboxylic acid

Participants

Reaction Steps

An autoclave was charged under argon in a glove box (O2 content<2 ppm) with 1-benzyl-4-(4-chloro-phenyl)-2,5-dihydro-1H-pyrrole-3-carboxylic acid (1.00 g, 3.19 mmol), [Ru(OAc)2((S)-2-furyl-MeOBIPHEP)] (9.72 mg, 0.01 mmol) (2-furyl-MeOBIPHEP=(6,6′-dimethoxybiphenyl-2,2′-diyl)bis(di-2-furylphosphine) and methanol (30 ml). The asymmetric hydrogenation was run for 20 h at 30° C. under 40 bar of hydrogen (>95% conversion, determined by NMR). After the pressure was released, the grey suspension was evaporated to dryness to yield 1.01 g of the crude title compound. The crude product was dissolved in methanol (15 mL) and heated to reflux for 1 h. After cooling to ambient temperature it was stirred for 2 h at 0° C. The resulting suspension was filtered and dried (40° C., 15 mbar) for 2 h. affording the title compound (0.984 g, 95%, e.e. 99.8% R,R (chiral HPLC)) as white solid. MS m/e: 316.1 [M+H]+.

Provenance & Evidence