Pseudo-prolines in cyclic peptides: Conformational stabilisation of cyclo[Pro-Thr(Ψ(Me,Me)pro)-Pro]
Linear peptide H-Pro-Thr(Ψ(Me,Me)pro)-Pro-OH containing a preformed cis-Pro-Thr(Ψ(Me,Me)pro) tertiary amide bond cyclises instantaneously and free of formation of oligomeric structures to the cyclic tripeptide cyclo- [Pro-Thr(Ψ(Me,Me)pro)-Pro]. Even at concentrations up to 10-1 M peptide, no oligomeric structures are detected by mass spectroscopy and HPLC. 2D 1H NMR studies of purified cyclotripeptide reveal the compound to exist in one single conformation with all peptide bonds in the cis conformation. These results indicate enhanced cyclisation tendencies of cis-amide bond containing peptides of short chain length.
A new facile one-pot preparation of pentafluorophenyl (Pfp) and 3,4-dihydro-4-oxo-1,2,3-benzotriazine-3-yl (Dhbt) esters of Fmoc amino acids
A new one-pot procedure for the preparation of pentafluorophenyl and 3,4-dihydro-4-oxo-1,2,3-benzotriazine-3-yl esters of Nα-9-fluorenylmethyloxycarbonyl amino acids bearing no side chain protecting groups is described. The method gives the desired activated esters in high yield and purity without use of the highly allergenic DCC.
Jacobsen, Mogens Havsteen,Buchardt, Ole,Engdahl, Tom,Holm, Arne
p. 6199 - 6202
(2007/10/02)
9-Fluorenylmethyl Pentafluorophenyl Carbonate as a Useful Reagent for the Preparation of N-9-Fluorenylmethyloxycarbonylamino Acids and their Pentafluorophenyl Esters
9-Fluorenylmethyl pentafluorophenyl carbonate is a useful reagent for the efficient, side reaction-free introduction of N-9-fluorenylmethyloxycarbonyl protecting group into amino acids and for the subsequent preparation of their pentafluorophenyl esters.Some new compounds of both types are described.
Schoen, Istvan,Kisfaludy, Lajos
p. 303 - 305
(2007/10/02)
Preparation and Applications of Pentafluorophenyl Esters of 9-Fluorenylmethyloxycarbonyl Amino Acids for Peptide Synthesis
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Kisfaludy, Lajos,Schoen, Istvan
p. 325 - 327
(2007/10/02)
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