Imaging glycans in vivo has recently been enabled using a bioorthogonal chemical reporter strategy by treating cells or organisms with azide- or alkyne-tagged monosaccharides. The modified monosaccharides, processed by the glycan biosynthetic machinery, are incorporated into cell surface glycoconjugates. The bioorthogonal azide or alkyne tags then allow covalent conjugation with fluorescent pro...

The synthesis of new multivalent architectures based on a trihydroxypiperidine α-fucosidase inhibitor is reported herein. Tetravalent and nonavalent dendrimers were obtained by means of the click chemistry approach involving the copper azide-alkyne-catalyzed cycloaddition (CuAAC) between suitable scaffolds bearing terminal alkyne moieties and an azido-functionalized piperidine as the bioactive ...

Enantioselective nickel-catalyzed arylative cyclizations of substrates containing a Z-allylic phosphate tethered to an alkyne are described. These reactions give multisubstituted chiral aza- and carbocycles, and are initiated by the addition of an arylboronic acid to the alkyne, followed by cyclization of the resulting alkenylnickel species onto the allylic phosphate. The reversible E/Z isomeri...

Alkyne-modified phospholipids can be unambiguously identified and differentiated from native species in complex mixtures by formation of dicobalthexacarbonyl complexes. This reaction is specific for alkynes and is unaffected by other glycerophospholipid-related moieties. Enrichment of cells with alkyne-derivatized fatty acids or glycerophospholipids followed by solid-phase sequestration and rel...

The effects of ligand and substrate choice on the Pd-catalyzed cyclization of alkyne-tethered cyclohexadienones were examined. In the presence of a chiral ligand, the enantioselectivity of the desymmetrization is remarkably sensitive to structural changes in both the ligand and the substrate. Additionally, the regioselectivity of the reaction (5- vs. 6-membered ring formation) is dependent on t...

A convenient, scalable synthesis of the supramolecular building block 7-deazaguanine-based urea (DeUG) is reported. Incorporation of reactive moieties (DeUG azide 10 and alkyne 11 for copper-catalyzed azide-alkyne cycloadditions, "click chemistry") and a demonstration of transesterification (DeUG glycol, 12) highlights the versatility. X-ray structures of DeUG and a DeUG x DAN heterocomplex wer...

The preparation of alkyne-modified ansamitocins by mutasynthetic supplementation of Actinosynnema pretiosum mutants with alkyne-substituted aminobenzoic acids is described. This modification paved the way to introduce a thiol linker by Huisgen-type cycloaddition which can principally be utilized to create tumor targeting conjugates. In bioactivity tests, only those new ansamitocin derivatives s...

A much improved route to 1,1'-bis(arylethynyl)ferrocenes comprising accessible thiolates on the aryl ring is reported. Unanticipated reactions between AcCl, TBAF-BBr3 and ferrocenyl-alkynes are also discussed, offering a rationale for previous synthetic difficulties.