Leucine, N-carboxy-, N-benzyl ester, L- → HCID 67626227, compound

Participants

Reaction Conditions

Reaction Steps

To a mixture of N-benzyloxycarbonyl-L-leucine (20 mmol, 5.3 g), 4-methoxy-1,2-phenylenediamine dihydrochloride (4.22 g, 20 mmol) and O-benzotriazole-N,N,N',N'-tetramethyl-uronium-tetrafluoroborate (TBTU) (6.58 g, 20.50 mmol) in 15 mL DMF cooled in an ice bath was added diisopropylethylamine (14 mL, 80 mmol). After stirring for 2 hours, ethyl acetate was added and the solution was washed with saturated NaHCO3 3 times and brine 3 times, dried (MgSO4), and concentrated. The crude product was dissolved in 30 mL acetic acid and the solution was heated at 65° C. for 2 hours. Acetic acid was removed by concentration under reduced pressure and the residue was purified on a silica gel column using methanol (3%)-methylene chloride as eluent to give 5.5 g (80%) product. m.p. 73°-77° C. ES-MS: calcd M+1 368.2; found 368.3.

Provenance & Evidence