p-Toluenesulfonic acid → HCID 58160377, compound

Participants

Reaction Conditions

Reaction Steps

0.5 g of 5-Biphenyl-4-ylmethyl-3-[1-dimethylamino-meth-(E/Z)-ylidene]-2-oxo-pyrrolidine-1-carboxylic acid tert-butyl ester (7-a, R1=Boc, R6=Me, R7=Me) are added to 5 ml of n-butane-1-thiol. After the addition of 0.2 g of p-toluenesulfonic acid the mixture is stirred for 6 days at 25° C., then heated to 60° C. for 16 hours. The mixture is then quenched by addition of 5 ml of an 8% aqueous bicarbonate solution and any remaining n-butane-1-thiol distilled off under reduced pressure at 40° C. The aqueous phase is extracted 3 times with 5 ml ethyl acetate each and the combined organic phase evaporated to dryness at 40° C. under reduced pressure. The residue is purified by column chromatography (heptane: ethyl acetate 75:25) to afford (3R/S,5S)-5-biphenyl-4-ylmethyl-3-(bis-butylsulfanyl-methyl)-2-oxo-pyrrolidine-1-carboxylic acid tert-butyl ester (16-a, R1=Boc, R9=nBu, R9=nBu, Y=S). Ratio of C-3 diastereomers determined as 70:30 ((3S,5S):(3R,5S) diastereomers, respectively). 1H NMR (CDCl3): Data for mixture of diastereomers: 0.86-0.96 (6H), 1.32-1.47 (4H), 1.50-1.68 (4H), 1.62 (9H), 1.94-2.30 (2H), 2.48-2.74 (4H), 2.80-2.89 (2H), 3.10-3.16 (1H), 3.55-3.59 (1H, minor stereoisomer), 4.23-4.31 (1H, minor stereoisomer), 4.30 (1H), 4.38 (1H, minor stereoisomer), 4.43-4.47 (1H), 7.27-7.30 (2H), 7.32-7.40 (1H), 7.44-7.50 (2H), 7.56-7.65 (4H).

Provenance & Evidence