Di-tert-butyl dicarbonate → (S)-2-biphenyl-4-ylmethyl-5-oxopyrrolidine-1-carboxylic acid t-butyl ester

Participants

Reaction Steps

8.6 g (S)-5-Biphenyl-4-ylmethylpyrrolidin-2-one (1-a, R1=H) (34.22 mmol) is dissolved in 135 ml methylene chloride. 4.2 g DMAP (34.22 mmol) is added. The mixture is further diluted with 10 ml methylene chloride. Then 14.9 g BOC2O (68.44 mmol) is added and further 10 ml methylene chloride is added. This reaction mixture is then stirred at reflux for 7.5 h. Then a further 3.7 g BOC2O is added. After a total reaction time of 24 h at reflux the solvent is evaporated completely. The evaporation residue is then filtered over 460 g of silica gel with an eluent of toluene:ethyl acetate 4:1. The product fractions are concentrated in vacuo to yield the crude product, which is recrystallised from methylene chloride/heptane fraction 1:6, to yield (S)-5-biphenyl-4-ylmethyl-2-oxo-pyrrolidine-1-carboxylic acid tert-butyl ester (1-a, R1=BOC).

Provenance & Evidence