Synthesis and NMR studies of malonyl-linked glycoconjugates ofN-(2-aminoethyl)glycine. Building blocks for the construction of combinatorial glycopeptide libraries.
Four glycoconjugate building blocks for the construction of combinatorial PNA like glycopeptide libraries were prepared in 75-79% yield by condensingtert-butylN-[2-(N-9-fluorenylmethoxycarbonylamino)ethyl]glycinate (AEG)5with 3-oxo-3-(2,3,4,6-tetra-O-acetyl-β-D-glucopyranosylamino)- (6a), 3-oxo-3-(β-D-galactopyranosylamino)- (6b), 3-oxo-3-(2-acetamido-2-deoxy-3,4,6-tetra-O-acetyl-β-D-glucopyranosylamino)- (6c) and 3-oxo-3-(2-acetamido-2-deoxy-3,4,6-tetra-O-acetyl-β-D-galactopyranosylamino)propanoic acid (6d), respectively. The resulting AEG glycoconjugates1a-dwere converted into the corresponding free acids2a-din 97-98% yield by treatment with aqueous formic acid. The Fmoc group of compound1cwas removed and the intermediate amine9was condensed with2ato afford the corresponding glycosylated AEG dipeptide4in 58% yield. All glycoconjugate building blocks showed the presence ofcisandtransrotamers. Compounds1a,1band4were subjected to temperature dependent1H NMR spectroscopy in order to determine the coalescence temperature which resulted in calculated rotation barriers of 17.9-18.3 kcal/mol for the rotamers.
Institute of Organic Chemistry, University of Tuebingen, Auf der Morgenstelle 18, 72076 Tuebingen, Germany.
Markus
M
Nörrlinger
Institute of Organic Chemistry, University of Tuebingen, Auf der Morgenstelle 18, 72076 Tuebingen, Germany.
Sven
S
Hafner
Institute of Organic Chemistry, University of Tuebingen, Auf der Morgenstelle 18, 72076 Tuebingen, Germany.
Thomas
T
Ziegler
N-(2-aminoethyl)glycine; amino acids; carbohydrates; glycoconjugates; glycopeptides