Ammonium Chloride → Methyl (S)-2-benzyloxycarbonylamino-4-oxo-5-phenylpentanoate

Participants

Reaction Conditions

Reaction Steps

In a baked-out, argon-purged flask, 3.7 g of lithium bromide (2.4 eq.) and 4.38 g (1.2 eq) of CuBr-Me2S were dissolved in 55 ml of abs. THF and stirred at RT for 20 min. The resulting yellow solution was cooled to −70° C. and admixed with 16.2 ml (1.2 eq.) of benzylmagnesium chloride solution (20% in THF). After a further 20 min at −70° C., a solution of 5.32 g of methyl (S)-2-benzyloxycarbonylamino-3-chlorocarbonylpropionoate (example 1) (17.75 mmol) in 15 ml of THF was added. After 2 h, the mixture was heated slowly to −35° C. and 50 ml of a sat. NH4Cl solution were added. The reaction mixture was diluted with 400 ml of dichloromethane and washed with 100 ml of a 2 M HCl solution. The aqueous phase was washed twice more with 50 ml of dichloromethane. The combined organic phases were washed successively with 2 M HCl solution, sat. NaHCO3 solution and sat. NaCl solution, dried over MgSO4 and concentrated under reduced pressure. Methyl (S)-2-benzyloxycarbonylamino-4-oxo-5-phenylpentanoate was obtained as a yellow oil which was used in the next stage without further purification.

Provenance & Evidence