(r)-5-Biphenyl-4-ylmethyl-3-[1-diisopropylamino-meth-(e)-ylidene]-2-oxo-pyrrolidine-1-carboxylic acid tert-butyl ester → (3R,5S)-5-biphenyl-4-ylmethyl-3-methyl-2-oxo-pyrrolidine-1-carboxylic acid tert-butyl ester

Participants

Reaction Conditions

Reaction Steps

1.3 g (R)-5-biphenyl-4-ylmethyl-3-[1-dimethylaminometh-(E/Z)-ylidene]-2-oxo-pyrrolidine-1-carboxylic acid tert-butyl ester (7-a, R1=Boc, R6=Me, R7=Me) is dissolved in 40 ml of ethyl acetate. After addition of 0.3 g 10% Pd/C (Engelhard 4505) the system is flushed several times with hydrogen and subsequently stirred at 20° C. and 4 bar hydrogen for 5 days. The resulting reaction mixture is filtered through cellflock and concentrated to dryness yielding (3R,5S)-5-biphenyl-4-ylmethyl-3-methyl-2-oxo-pyrrolidine-1-carboxylic acid tert-butyl ester (3-a, R1=Boc) and (3S,5S)-5-biphenyl-4-ylmethyl-3-methyl-2-oxo-pyrrolidine-1-carboxylic acid tert-butyl ester (3-b, R1=Boc). Diastereomer ratio 33:67 (3-a, R1=Boc: 3-b, R1=Boc) as determined by hplc.

Provenance & Evidence