4-Methylmorpholine → Fmoc-Glu(OBut)-Arg(Pmc)-Val-Asp(Allyl)-OBzl

Participants

Reaction Conditions

Reaction Steps

To a solution of Fmoc-Glu(tBu) (6.73 g, 15.8 mmol) and benzotriazolyloxy-tris[pyrrolidino]-phosphonium hexafluoroacetate (PyBOP, 8.18 g, 15.8 mmol) in 105 mL acetonitrile at 2° C. is added N-methylmorpholine (1.58 g, 15.8 mmol) and the reaction mixture is stirred at 2-4° C. for 30 minutes. A solution of L)Arg(Pmc)-Val-Asp(OAllyl)-OBzl (12.4 g, 15.8 mmole) in 70 mL acetonitrile is added at 2° .C over 20 minutes. N-methylmorpholine is then added to achieve pH 7. Cooling is ceased, and the mixture is allowed to warm to ambient temperature, then stirred is continued for a total of 3 hours. The milky reaction mixture is filtered (slow) and the white residue is dried in the filter overnight to afford 10.8 g of Fmoc-Glu(OBut)-Arg(Pmc)-Val-Asp(Allyl)-OBzl. The filtrate is concentrated to give a gum, which is taken up in 30 mL acetonitrile and allowed to stand for 48 hours, producing an additional 3.45 g of product. The total yield of Fmoc-Glu(OtBu)-Arg(Pmc)-Val-Asp(OAllyl)-OBzl is 14.3 g. (Mcalc 1192; M+1obsvd 1192.4)

Provenance & Evidence