Sulfuric Acid → (5R)-5-([1,1′-Biphenyl]-4-ylmethyl)-2-pyrrolidinone

Participants

Reaction Conditions

Reaction Steps

14 g of (R)-5-(biphenyl-4-carbonyl)pyrrolidin-2-one are suspended in 80 ml tetrahydrofuran. Subsequently 331 mg of concentrated sulphuric acid are added and the reaction vessel is purged with argon. 1.4 g of palladium on carbon 10% m/m (W. C. Heraeus GmbH, Type K-0218) is added and the mixture is stirred under an atmosphere of hydrogen (3 bar) at 30° C. for 20 h. The black suspension is filtered and the filter cake is washed with tetrahydrofuran. After the addition of 50 ml water, the pH of the emulsion is adjusted to pH 5.5 using sodium hydroxide solution (2M). Under reduced pressure, the organic solvent is removed and 100 ml of isopropyl acetate are added. The aqueous layer is then separated and the remaining organic layer is concentrated to approx. half of its original volume. The suspension is cooled to −5° C. and filtered. The filter cake is washed with cooled isopropyl acetate and is dried under reduced pressure to give (R)-5-biphenyl-4-ylmethylpyrrolidin-2-one as colourless crystals. 1H-NMR (CDCl3): 1.93 (1H); 2.37 (3H); 2.80 (1H, dd, J=8.5, 13.5); 2.92 (1H, dd, J=5.4, 13.5); 3.95 (1H); 5.70 (1H); 7.29 (1H, d, J=7.5); 7.38 (1H); 7.47 (2H); 7.59 (4H). MS (ESI, m/e) 252 [M+H]+; 503 [2M+H]+. IR (solution in CH2Cl2, □/cm−1): 3191; 3055; 2930; 1692; 1489; 1272; 762; 692.

Provenance & Evidence