The palladium-catalyzed Sonogashira-type aerobic oxidative coupling of arylhydrazines with terminal alkynes via C-N bond cleavage has been developed; internal alkynes were afforded with a broad substrate scope. This reaction proceeds under copper- and base-free conditions with molecular oxygen as the sole oxidant and nitrogen and water as the only by-products.

A copper(I)-phosphine complex has been found to facilely promote the distannylation of alkynes with the aid of a base, where a catalytically generated Cu-Sn species serves as a key intermediate. The broad versatility of the copper catalysis has been demonstrated by the facile distannylation of unfunctionalized aliphatic alkynes, being hardly achievable with the conventional palladium catalysts.

BCl3 is an inexpensive electrophile which induces the borylative cyclization of a wide range of substituted alkynes to regioselectively form polycycles containing synthetically versatile C(sp(2) )boronate esters. It proceeds rapidly, with good yields and is compatible with a range of functional groups and substitution patterns. Intermolecular 1,2-carboboration of alkynes is also achieved using...

The importance of cyclopentanoid natural products continues to inspire the development of methods for the synthesis of 5-membered rings. For example, the Conia–ene reaction provides an atomeconomical synthesis of methylenecyclopentanes by the thermal cyclization of e-acetylenic carbonyl compounds. While the classic thermal reaction is limited to the exocyclic cyclization mode, group 6 metal com...

a,b-Unsaturated carboxylic acids are important chemicals, and can be used as basic materials in the production of plastics, superabsorbent, polymers, and rubbers. Various synthetic methodologies for their synthesis have been developed, for example, oxidation of propene over heterogeneous catalysts at high temperature yielded the a,b-unsaturated carboxylic acids and hydrocarboxylation of alkynes...

Cross-dimerization of various terminal alkynes with different bulky terminal alkynes such as triisopropylsilylacetylene and 1-trimethylsilyloxy-1,1-diphenyl-2-propyne efficiently proceeds in the presence of a rhodium catalyst system to produce the corresponding (E)-enynes with high regio- and stereoselectivity.

A novel rhodium-catalyzed linear codimerization of alkyl phenyl ketenes with internal alkynes to dienones and a novel synthesis of furans by an unusual cycloaddition of diaryl ketenes with internal alkynes have been developed. These reactions proceed smoothly with the same rhodium catalyst, RhCl(PPh(3))(3), and are highly dependent on the structure and reactivity of the starting ketenes.

Phenyl- and vinyllithiums having an alkyl substituent at their ortho- and cis-position, respectively, readily added to alkynes in the presence of 5 mol% of Fe(acac)(3). The reaction of o-(trimethylsilyl)phenyllithium with alkynes gave benzosiloles through an addition-cyclization sequence.

An intriguing new Wacker-type oxidation of alkynes catalyzed by PdBr(2) and CuBr(2) is described, which opens an efficient access to 1,2-diketones using molecular oxygen. Under the optimized conditions, a variety of alkynes, including diarylalkynes, arylalkylalkynes, and dialkylalkynes, were compatible substrates in this transformation. The mechanism of this reaction was preliminarily investiga...

Conditions are reported for the facile, high-yielding coupling of acyl chlorides with terminal alkynes in a reaction involving palladium and copper iodide; the reaction is tolerant of a wide variety of acyl chlorides and terminal alkynes and provides a convenient one-pot route to acetylenic ketones.