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An efficient synthetic organic transformation was developed to access isoquinoline-substituted isobenzofurans by reaction of substituted 1,5-diynes with isoquinoline N -oxides. Moderate to excellent yields of isoquinoline-derived isobenzofurans were achieved by formation of a new C-C and two C-O bonds in the presence of copper catalyst in one pot. whereas quinoline-substituted isobenzofurans were obtained when the reaction was conducted using quinoline N -oxides and 1,5-diynes in the presence copper catalyst.

Nonafluorobutanesulfonyl azide is a highly efficient reagent for the copper-catalyzed coupling of terminal alkynes to give symmetrical and unsymmetrical 1,3-diynes in good to excellent yields and with good functional group compatibility. The reaction is extremely fast (<10 min), even at low temperature (−78 °C), and requires substoichiometric amounts of a simple copper(I) or copper(II) salt (2–5 mol %) and an organic base (0.6 mol %). A possible mechanistic pathway is briefly discussed on the basis of model DFT theoretical calculations. The quantitative assessment of the safety of use and shelf stability of nonafluorobutanesulfonyl azide has confirmed that this reagent is a superior and safe alternative to other electrophilic azide reagents in use today.

An efficient cross-coupling of alkynes with alkynyl and alkenyl halides catalysed by a Ni-Cu system without any ligand has been achieved. The reaction is suggested to proceed by Ni(0) catalysis assisted by Cu(I). A series of functionalised diaryl, aryl-alkyl, aryl-heteroaryl, diheteroaryl 1,3-di-ynes and en-ynes are obtained in high yields.

An efficient Csp-Csp cross-coupling of alkynyl bromide and pinacol ester of alkynyl boronic acid catalyzed by CuFe2O4 nanoparticles has been accomplished in dimethyl carbonate to produce unsymmetric 1,3-diynes. This protocol is also extended for the Csp-Csp2 coupling of alkynyl bromide and alkenyl boronic acid to provide conjugated 1,3-enynes. The aliphatic, aromatic, and heteroaromatic alkynes couple with various substituted alkynyl/alkenyl boronates/boronic acids by this procedure to furnish a library of 1,3-diynes and enynes in high yields. The catalyst was easily separated by an external magnet and recycled 10 times.

Diynes containing a cyclopropane group smoothly undergo a novel intramolecular and stereoselective cascade addition/cyclization reaction to produce the corresponding 1-methyleneindene derivatives in moderate to good yields. This interesting transformation is mediated by Grignard reagent/CuI with LiCl as an additive under mild conditions. The obtained product can easily be further functionalized through cyclopropyl ring opening. A plausible reaction mechanism has also been presented on the basis of deuterium labeling and control experiments., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

An efficient Sonogashira coupling of terminal alkynes and styrenyl bromides has been achieved under the catalysis of hydroxyapatite-supported copper(I). The trans-styrenyl bromides produce the usual trans-enyne products, whereas the cis-styrenyl bromides lead to unsymmetric 1,3-diynes by the cross coupling of terminal alkyne and the alkyne generated from the cis-styrenyl bromide. A series of trans-enynes and unsymmetric 1,3-diynes have been synthesized by this protocol.

A regioselective synthesis of 2,5-disubstituted furans using copper(I) catalyst from haloalkynes in a one-pot procedure has been reported. This chemistry proceeds through the hydration reaction of 1,3-diynes, which can be readily prepared from the coupling reaction of haloalkynes in the presence of CuI. The procedure also can be used for the facile synthesis of 2,5-disubstituted thiophenes.

A one-pot protocol for the synthesis of triazole-annulated polyheterocycles via metal-catalyzed coupling of internal 1,4-disubstituted 1,3-diynes and organic azides has been described. The mechanistic rationale for the reaction suggests tandem cyclizations involving copper-catalyzed cycloaddition and 6-endo carbocyclization reactions. The cascade cyclization leads to an increase in molecular complexity to furnish naphtho[1,2-d]triazoles in satisfactory yields. The generality of the method has been demonstrated by using a series of aromatic/aliphatic azides and symmetrical internal 1,3-diynes., (© 2011 American Chemical Society)

Two azo-ene-butadiyne conjugated systems undergo CuCl-mediated cyclization to afford isoindazolyl carbenoids that could be trapped with 2,3-dimethyl-2-butene as [2+1] cycloaddition products. X-ray structure analysis of the resultant cyclopropanes showed that formal migration to the distal carbenoid isomer and subsequent trapping had occurred. The possible CuCl-induced cyclization/migration pathways were explored using density functional theory, which indicated that the reaction most likely occurred via coordination of CuCl to the distal alkyne bond.