Sodium Hydroxide → (3S,5R)-5-Biphenyl-4-ylmethyl-3-methyl-2-oxo-pyrrolidine-3-carboxylic acid

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Reaction Steps

252 mg (3R,5R)-5-Biphenyl-4-ylmethyl-1-(2,2-dimethylpropionyl)-3-methyl-2-oxo-pyrrolidine-3-carboxylic acid ethyl ester (R1=Piv; R10=OEt; R11=Me) [62:38 mixture of C3-isomers] is added to 1 ml acetonitrile at 0° C. 0.3 ml 3 M Sodium hydroxide solution is added and the mixture stirred at room temperature for 20 h. Two further 50 μl portions of 3 M sodium hydroxide are added. Stirring is continued for another 2 h. The mixture is concentrated in vacuo. 2.5 ml of water is added to the residue and it is then extracted twice with 1 ml toluene. 5 ml Ethyl acetate is added to the aqueous phase, which is then cooled to 0° C. 500 μl 2 M Hydrochloric acid is added and the phases are separated. The aqueous phase is then extracted with ethyl acetate. The combined organic phases are combined, dried (MgSO4) and concentrated in vacuo to afford (3R,5R)-5-Biphenyl-4-ylmethyl-3-methyl-2-oxo-pyrrolidine-3-carboxylic acid (R1=H; R10=OH; R11=Me) and (3S,5R)-5-Biphenyl-4-ylmethyl-3-methyl-2-oxo-pyrrolidine-3-carboxylic acid (R1=H; R10=OH; R11=Me). According to HNMR analysis there is a 66:34 mixture of C3-stereoisomers. Identity of major isomer not determined. 1H NMR (DMSO) [mixture of stereoisomers]: 1.21 (3H), 1.59, 1.84, 2.20, 2.29 (total 2H), 2.66 (1H), 2.93 (1H), 3.81 (1H), 7.31 (3H), 7.44 (2H), 7.60 (4H), 8.10, 8.15 (total 1H), 12.58 (1H).

Provenance & Evidence