C-Glycosyl Tyrosines. Synthesis and Incorporation into C-Glycopeptides.
The synthesis of the Fmoc-protected C-glycosyl tyrosines 1 and 2, together with two other related C-glycosyl tyrosines, has been achieved. Key reactions involved (i) the reaction of a glycal with an organozinc reagent (carrying an aryl iodide function) in the presence of a Lewis acid to establish the C-glycosyl linkage and (ii) subsequent cross coupling of the aryl iodide to an alanyl zinc reagent (in the presence of a Pd(0) catalyst) to complete the construction of the alpha-amino acid moiety. Using solid-phase peptide synthesis methods, two units of the mannosyl derivative 1 (shown as L-Tyr[C-Ac(4)-alpha-D-Man]) have been incorporated (with four units of glycine) into the linear hexapeptide 3 which was then converted to the C(2)-symmetric cyclic oligopeptide 4.
Pearce
Alan J.
AJ
School of Chemistry, University of Bristol, Bristol, BS8 1TS, UK, Department of Biochemistry, Medical School, University of Bristol, Bristol, BS8 1TD, UK, and Roche Discovery Welwyn, Welwyn Garden City, AL7 3AY, UK.
Ramaya
Sharn
S
Thorn
Simon N.
SN
Bloomberg
Graham B.
GB
Walter
Daryl S.
DS
Gallagher
Timothy
T