As chitosan’s solubility represents a drawback for further applications, the functionalization of chitosan became attractive by a variety of chemical methods. The present study deals with the chemical modification of chitosan by using click chemistry technique as versatile tool being easy to perform with high yields and no additional by products. The approach used herein was to attach a respons...

A modular synthetic method for bis- and tris-1,2,3-triazoles that include a benzotriazole structure was developed on the basis of sequential azide-aryne and azide-alkyne cycloadditions. The key to success was efficient halogen-metal exchange reaction-mediated generation of aryne from ortho-iodoaryl triflates bearing a base-sensitive terminal alkyne moiety, which was achieved using trimethylsily...

Alcohol is the answer! An inactive, air-stable, dimeric molybdenum alkylidyne complex is activated toward ring-opening alkyne metathesis polymerization (ROAMP) by the addition of methanol. The ROAMP is compatible with water and phenol-containing substrates and with the in situ photochemical generation of alkyne monomers from cyclopropenones.

A simple and convenient method for the preparation of ultra-small palladium nanoparticles (Pd-NPs) by a modified digestive ripening method is described. These nanoparticles catalyse the hydrogenation of the terminal alkyne groups to alkanes selectively, and show no effect on other labile protecting and internal alkyne or internal/external alkene groups present in the molecule.

Alkyne metathesis by molybdenum and tungsten alkylidyne complexes is now ~45 years old. Progress in the practical aspects of alkyne metathesis reactions with well-defined complexes, as well as applications, in the last decade, guarantees that it is destined to become a useful method for the synthesis of organic molecules.

A concise synthesis of a useful intermediate 10 for the preparation of fingolimod (FTY-720) analogs was achieved by utilizing a chemoselective Sonogashira reaction of trihalobenzene 12 with alkyne 13. The reaction proceeded with high selectivity to give alkyne 11 containing the dihalobenzene moiety in good yield. Compound 11 was converted into intermediate 10 by hydrogenation without reduction ...

o-Alkynylarenenitriles when heated with Pd(OAc)2/H2O/(±)-CSA in DMSO undergo simultaneous alkyne oxidation and nitrile hydration to give 3-aryl-3-hydroxy-2,3-dihydroazanaphthoquinones. Upon treatment with (±)-CSA, these compounds form 3-arylazanaphthoquinones in situ, which add to electron-rich aromatics and terminal alkene/alkyne to afford 3,3-disubstituted-2,3-dihydroazanaphthoquinones.

The reaction of acetylides with sulfonyl azides was found to selectively form 1,5-substituted sulfonyl triazoles. This reaction thus provides access to the regioisomeric product as compared to the popular copper-catalyzed azide-alkyne cycloaddition. The reaction is efficient and selective with a variety of alkyne sources and sulfonyl azides and can incorporate an additional electrophile to yiel...

An alkyne-azide addition, i.e., click, reaction in conjunction with an electrostatic self-assembly and covalent fixation (ESA-CF) process has been demonstrated to effectively construct a variety of unprecedented multicyclic polymer topologies. A series of single cyclic poly(tetrahydrofuran), poly(THF), precursors having an alkyne group (Ia), an azide group (Ib), two alkyne groups at the opposit...

The development of robust tools and practical RNA labeling strategies that would facilitate the biophysical analysis of RNA in both cell-free and cellular systems will have profound implications in the discovery of new RNA diagnostic tools and therapeutic strategies. In this context, we describe the development of a new alkyne-modified UTP analog, 5-(1,7-octadinyl)uridine triphosphate (ODUTP), ...