Citric Acid → HCID 66739033, compound

Participants

Reaction Conditions

Reaction Steps

44 mg (3R/S, 5R)-5-Biphenyl-4-ylmethyl-3-methyl-2-oxo-pyrrolidine-3-carboxylic acid (R1=H; R10=OH; R11=Me) [66:34 mixture of C3-stereoisomers] are added to 10 ml toluene. 119 μl Triethylamine are added and the resulting mixture warmed to 60° C. 52 μl Pivaloyl chloride are added and the mixture is stirred for 4 h. The mixture is then cooled to room temperature. 250 mg Citric acid in water (5 ml) is added and the phases are separated. The organic phase is washed with water, dried (MgSO4) and concentrated in vacuo to give (3R,5R)-5-Biphenyl-4-ylmethyl-1-(2,2-dimethylpropionyl)-3-methyl-2-oxo-pyrrolidine-3-carboxylic acid (R1=Piv; R10=OH; R11=Me) and (3S,5R)-5-Biphenyl-4-ylmethyl-1-(2,2-dimethylpropionyl)-3-methyl-2-oxo-pyrrolidine-3-carboxylic acid (R1=Piv; R10=OH; R11=Me). According to HNMR analysis the ratio of C3 diastereoisomers is 65:35. Identity of major diastereomer not determined. 1H NMR (CDCl3) [Mixture of stereoisomers]: 1.19 (9H), 1.21 (3H), 1.73-1.91 (1H), 2.23 (1H), 2.50 (2H), 3.12-3.33 (1H), 4.45-4.60 (1H), 7.19 (1H), 7.27 (2H), 7.37 (2H), 7.46 (4H).

Provenance & Evidence