4-Methylmorpholine → FMOC-Asp(OBzl)-Glu(O-tBu)-Tyr(Bzl)-OBzl

Participants

Reaction Conditions

Reaction Steps

FMOC-Asp(OBzl) (4.45 g; 10 mmol) was dissolved in ethyl acetate (30 ml) and cooled down to -15° C. Isobutylchloroformate (1.5 ml; 11 mmol) was added to the solution, followed by N-methylmorpholine (1.2 ml; 11 mmol). FMOC-Glu(O-t-Bu)-Tyr(Bzl)-OBzl (29) (6 g; 7.8 mmol) was treated with 10% piperidine in dimethylformamide (100 ml) for 1 h. The solvent was removed under reduced pressure and the residue was dissolved in dimethylformamide (30 ml) and added to the first solution at -15° C. The reaction mixture was stirred overnight at ambient temperature. Solids were removed by filtration and under reduced pressure. The residue was dissolved in ethylacetate (150 ml) and the insoluble material was removed by filtration. The organic solution washed with 0.05N hydrochloric acid (3×40 ml), water (40 ml) and dried over anhydrous sodium sulfate. The drying agent was removed by filtration and the filtrate evaporated under reduced pressure. The residue was crystallized from ethylacetate/petroleum ether to give 5.5 g (72 percent) of 30, m.p. 96°-99° C.

Provenance & Evidence