1,2-Dichloroethane → 3(S)-(2-((2(S)-Benzoylamino-3-methylbutyryl)benzylamino)acetylamino)-4-oxo-butyric Acid tert-Butyl Ester Semicarbazone

Participants

Reaction Steps

To a solution of 3(S)-(1-fluorenylmethyloxycarbonylamino)-4-oxobutyric acid tert-butyl ester semicarbazone (678 mg, 1.5 mmol; Prepared in a similar manner to the benzyloxycarbonyl analog in Graybill et al., Int. J. Protein Res. , 44, pp. 173-82 (1994)) in acetonitrile (5.0 mL) was added diethylamine (780 μL, 7.5 mmol) and the reaction allowed to stir at rt for 1 hr. The reaction was concentrated in vacuo and the residue co-concentrated with toluene (3×) in vacuo. To a suspension of the residue, compound 704 (555 mg, 1.5 mmol) and HOBT (224 mg, 1.66 mmol) in 1:1 CH2Cl2 :DMF (10 mL) at 0° C., was added EDC (318 mg, 1.66 mmol). The reaction was warmed to rt and stirred over night. The reaction was diluted with EtOAc and H2O. The layers were separated and the organic phase washed with sat. aq. NaHCO3, sat. aq. KHSO4, brine, dried over MgSO4, filtered and concentrated in vacuo. Chromatography of the residue on silica gel (elution with 2-6% MeOH:CH2Cl2) provided 600 mg of compound 705. ##STR84##

Provenance & Evidence