DBU-Catalyzed transprotection of N-Fmoc-cysteine di- and tripeptides into S-Fm-cysteine di- and tripeptides
作者:Alan R. Katritzky、Nader E. Abo-Dya、Abdelmotaal Abdelmajeid、Srinivasa R. Tala、M. S. Amine、Said A. El-Feky
DOI:10.1039/c0ob00663g
日期:——
The transprotection of N-Fmoc-cysteine containing di- and tripeptides possessing a free SH group to produce the corresponding S-Fm-cysteine di- and tripeptides bearing a free amino group is accomplished efficiently with DBU in dry THF. The N-Fmoc to S-Fm transformation mechanism is discussed. S-Fm-Cysteine di- and tripeptides readily form amide bonds on coupling with N-(Pg-α-aminoacyl)benzotriazoles and N-(Pg-α-dipeptidoyl)benzotriazoles to give larger peptides.
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 cyclictransitionstates. 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 cyclictransitionstates from the S-atom of a cysteine residue to a peptide terminal amino group to form native