N-Cbz-protected β-amino acids, which were subjected to an N-Cbz/N-Fmoc (Fmoc=[(9H-fluoren-9-yl)methoxy]carbonyl) protective-group exchange. The method is suitable for large-scale preparation of Fmoc-β2hXaa-OH for solid-phase syntheses of β-peptides. The Fmoc-amino acids and all compounds leading to them have been fully characterized by melting points, optical rotations, IR, 1H- and 13C-NMR, and mass spectra
三个新的制备Ñ -Fmoc保护的羰基(Fmoc = [(9 ħ
芴-9-基)甲
氧基]羰基)β 2 -homoamino
羧酸与蛋白原侧链(距离Ile,Tyr和Met)的描述,所述关键步骤是用CbzNHCH 2 OMe / TiCl 4(Cbz =(苄
氧基)羰基)将3-酰基-4-
异丙基-5,5-二
苯基
恶唑烷-2-
酮的相应
钛烯酸
酯进行非对映选择性
酰胺甲基化,产率为60– 70%的非对映选择性> 90%。用LiOH或NaOH去除手性助剂得到N -Cbz保护的β-
氨基酸,这些
氨基酸经过N -Cbz / N -Fmoc处理(Fmoc = [(9 H-
芴-9-基)甲
氧基]羰基)保护基交换。该方法适用于的Fmoc-大规模制备β 2 hXaa-OH用于固相合成β -肽。Fmoc-
氨基酸和所有导致它们的化合物已通过熔点,旋光度,IR,1 H-和13 C-NMR,质谱以及元素分析充分表征。