Chemical Ligation of S-Scylated Cysteine Peptides to Form Native Peptides via 5-, 11-, and 14-Membered Cyclic Transition States
作者:Alan R. Katritzky、Srinivasa R. Tala、Nader E. Abo-Dya、Tarek S. Ibrahim、Said A. El-Feky、Kapil Gyanda、Keyur M. Pandya
DOI:10.1021/jo1015757
日期:2011.1.7
5-membered cyclic transition states. Microwave irradiation of S-(Pg-α-aminoacyl)tripeptide 15 and S-(Pg-α-aminoacyl)tetrapeptide 17 in the presence of NaH2PO4/Na2HPO4 buffer solution at pH 7.8 achieved chemical ligations, involving intramolecular migrations of acyl groups, via 11- and 14-membered cyclic transition states from the S-atom of a cysteine residue to a peptide terminal amino group to form native
含半胱氨酸的二肽3a - 1,(3b + 3b')(括号中的化合物表示外消旋混合物;因此(3b + 3b')是3b和3b'的外消旋物),三肽13于68中合成在存在以下情况下,通过将N-(Pg-α-氨酰基)-和N-(Pg - α-二肽基)苯并三唑(其中Pg代表整个术语中的肽命名法中的保护基)酰化半胱氨酸可得−96%的产率Et 3 N.含半胱氨酸的肽3a - l和13用N-(Pg - α-氨基酰基)苯并三唑将S-(Pg-α-氨基酰基)二肽5a - 1和S-(Pg-α-氨基酰基)三肽14未经消旋化,得到47-90%的产率2在CH 3 CN-H 2 O(7:3)中KHCO的存在3。(在我们的肽命名法中,前缀di-,tri-等是指主肽链中氨基酸残基的数目;与硫连接的氨基酸残基称为S-酰基肽。因此,我们避免使用前缀“ iso”。)3k丝氨酸肽的选择性S-酰化因此,分别以58%和72%的产率获得了含有游