Propargyl Amides as Irreversible Inhibitors of Cysteine Proteases—A Lesson on the Biological Reactivity of Alkynes Are aliphatic alkynes truly bioorthogonal? In an attempt to prepare clickable ubiquitin derivatives bearing a C-terminal propargyl amide, two groups have now independently discovered propargylamides to be irreversible inhibitors of cysteine proteases. The unexpected findings demons...

Bacillus megaterium flavocytochrome P450 BM3 (BM3) is a high activity fatty acid hydroxylase, formed by the fusion of soluble cytochrome P450 and cytochrome P450 reductase modules. Short chain (C6, C8) alkynes were shown to be substrates for BM3, with productive outcomes (i.e. alkyne hydroxylation) dependent on position of the carbon-carbon triple bond in the molecule. Wild-type P450 BM3 cataly...

the synthesis of a novel class of 2-oxoindolin-3-ylidene-(1-arylhydrazinyl)-2-aryl(alkyl)ethylidene derivativesvia a copper-catalyzed tandem reaction of isatin, arylhydrazines, sulfonyl azides and terminal alkynes is described.

Novel bidentate amidines were designed and synthesized as easily available electron-donating N-ligands for Ni0-mediated coupling of carbon dioxide with alkynes or allenes, and high regioselectivity was achieved even for the carboxylation of aryl substituted internal alkynes.

Supported gold nanoparticles catalyze the semihydrogenation of alkynes to alkenes with ammonia borane or amine borane complexes in excellent yields and under mild conditions. Internal alkynes provide cis-alkenes, making this protocol an attractive alternative of the classical Lindlar's hydrogenation.

Heteroatom addition reactions to unactivated alkynes are thought to be best mediated by transition-metal catalysts such as palladium and gold. Recent studies by Hammond and co-workers and others demonstrate that cyclizations of alkynes with nitrogenand oxygen-containing nucleophiles are possible using stoichiometric amounts of tetra-n-butylammonium fluoride. However, these examples appear to be...

Cascade reactions initiated by radical addition to alkynes are synthetically very attractive because they enable access to highly complex molecular skeletons in only few synthetic steps under usually mild conditions. Here we report a general radical cascade reaction of alkynes, N-fluoroarylsulfonimides and alcohols, enabling the efficient synthesis of important α-amino-α-aryl ketones from readi...

Cobalt complex/Zn systems effectively catalyze the reductive coupling of activated alkenes with alkynes in the presence of water to give substituted alkenes with very high regio- and stereoselectivity in excellent yields. While the intermolecular reaction of acrylates, acrylonitriles, and vinyl sulfones with alkynes takes place in the presence of CoI2(PPh3)2/Zn, the reaction of enones and enals...

Gold-catalyzed hydroimination of terminal alkynes, giving rise to anti-Markovnikov adducts concomitant with unstable Markovnikov adducts is described. The elementary step can be applied for the construction of pyridine derivatives from ammonia and alkynes.

Cp*RuCl(PPh3)2 is an effective catalyst for the regioselective "fusion" of organic azides and terminal alkynes, producing 1,5-disubstituted 1,2,3-triazoles. Internal alkynes also participate in this catalysis, resulting in fully substituted 1,2,3-triazoles.