S-Fluorenylmethyl protection of the cysteine side chain upon N^α-Fmoc deprotection

• Johannes W. Wehner and
• Thisbe K. Lindhorst

Beilstein J. Org. Chem. 2012, 8, 2149–2155, doi:10.3762/bjoc.8.242

• transprotection reaction was studied. Keywords: Fmoc protecting group; glycoamino acids; N-Fmoc→S-Fm transprotection; protecting groups; Introduction In the course of our work on the synthesis of glycoamino acids, we have recently used L-cysteine as a scaffold for the synthesis of various glycoclusters [1][2][3

• methods, NCL or SPPS. In addition, mannosidic glycoamino acids are of interest as ligands for mannose-specific lectins in solution [17] as well as for the fabrication of glycoarrays on solid support [10][18][19]. Moreover, we are interested to advance glycoamino acid deriatives such as 3 into ligands that

• can be “switched” between two states by oxidation/reduction. A key step, when glycoamino acids are further conjugated, is Fmoc protection and deprotection. Here, we have shown an N-Fmoc→S-Fm transprotection reaction, which can occur upon N-Fmoc deprotection, and how it can be controlled under

En route to photoaffinity labeling of the bacterial lectin FimH

• Thisbe K. Lindhorst,
• Michaela Märten,
• Andreas Fuchs and
• Stefan D. Knight

Beilstein J. Org. Chem. 2010, 6, 810–822, doi:10.3762/bjoc.6.91

• two steps gave the Fmoc-protected biotin-labeled glycoamino acids 9 and 10, respectively. Fmoc-cleavage and peptide coupling with the diazirine 11 led to the target molecules 12 and 13 in good yield. To test the prepared photoactive mannosides in crosslinking reactions, the model peptide angiotensin

• (Table 3). Synthesis of photoactive glycoamino acids 11 and 12. i) Fmoc-Asp-OtBu (for 7), Fmoc-Asp(OtBu)-OH (for 8), HATU, DIPEA, dry DMF, N2, RT, 95% for 7 and 96% for 8; ii) 80% aq TFA, RT; iii) (+)-biotinylamidopropylammonium trifluoroacetate, HATU, DIPEA, dry DMF, N2, RT, 48% (two steps) for 9 and 26

(Pseudo)amide-linked oligosaccharide mimetics: molecular recognition and supramolecular properties

• José L. Jiménez Blanco,
• Fernando Ortega-Caballero,
• Carmen Ortiz Mellet and
• José M. García Fernández

Beilstein J. Org. Chem. 2010, 6, No. 20, doi:10.3762/bjoc.6.20

• structure [23][25]. Linear non-naturally-occurring SAA homo-oligomers The first examples of amide-linked SAA-pyranose oligomers were reported as long ago as 1975 by Fuchs and Lehman [26][27]. In 2002, Ichikawa and co-workers developed a synthetic methodology to access oligomers of glycoamino acids, a family

• relationships in order to design novel biologically active analogues of potential therapeutic value. Schematic representation of sugar aminoacids (SAAs) and (pseudo)amide oligosaccharide mimetics. Natural SAAs structures and natural nucleosidic antibiotics. The general structure of glycoamino acids and their