反应详情

834 mg of HBTU and 0.24 ml of N-methylmorpholine were added at 0° C. under argon to a solution of 446 mg of Z-β-Al-a-OH and 785 mg of H-Asp(O-tBu)-Phe-O-tBu (obtained from the condensation of Z-Asp(O-tBu)-OH with H-Phe-O-tBu followed by hydrogenolysis). After 5 hours, the mixture was concentrated and the residue was partitioned in ethyl acetate/5% NaHCO3. The organic phase was washed with water and 1M KHSO4. The organic extracts were dried, filtered and concentrated. The residue was recrystallised from ethyl acetate/diisopropyl ether resulting in 592 mg of Z-β-Ala-Asp(O-tBu)-Phe-O-tBu, m.p. 138°-139° C.