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The three-component coupling of benzynes with terminal alkynes and activated alkenes in the presence of CuI, PCy3and CsF in a 1 : 1 mixture of CH3CN and THF at 50 °C for 5 h gave 1-alkyl-2-alkynylbenzenes in good to moderate yields. [ABSTRACT FROM AUTHOR]

o-Dihaloarenes acting as aryne precursors react with acetylenes and nitriles catalyzed by the NiBr2(dppe)/dppe/Zn system to give substituted naphthalene, phenanthridine or triphenylene derivatives depending on the reaction conditions in moderate to excellent yields with good tolerance of functional groups. [ABSTRACT FROM AUTHOR]

Benzynes react with allylic acetates or halides and terminal alkynes in the presence of Pd(PPh3)4, CuI and CsF in CH3CN at 50 °C for 5 h to give 1-allyl-2-alkynylbenzene derivatives in good to excellent yields. [ABSTRACT FROM AUTHOR]

Demonstrates the catalysis of the diboration of allenes through palladium complexes and organic iodides. Instability of the oxidative addition products of diboron compounds; Efficacy of the alkenyl or aryl iodides as catalysts; Application of the catalytic mechanism to unsaturated organic systems.

The article discusses the study on the new method for the synthesis of phenanthrone derivatives from sec-alkyl aryl ketones and aryl iododes catalyzed by palladium acetate in trifluoroacetatic acid. It notes that palladium-catalyzed direct transformations of inactive carbon (C) - hydrogen (H) bonds into various functional groups has emerged as a powerful method in organic synthesis. It cites that the catalytic reaction proceeds via a dual C - H activation and enolate cyclization.

The article provides information related to cobalt-catalyzed diastereoselective reductive cycloaddition of allenes and enones. The cycloaddition reaction is one of the primary methods to construct five-membered carbocycles, which are common structural cores of a large number of biologically important natural products and target molecules for numerous synthetic studies.

Presents information on nickel-catalyzed highly regio-and stereoselective three-component assembly of allenes, aryl iodides and alkenylzirconium reagents. Catalytic conditions in the absence of either nickel catalyst or zinc powder; Results for the three-component assembly of various allenes, aryl iodides and zirconium reagents catalyzed by NiCI[sub2](PPh[sub3])[sub2] and zinc powder in THF; Mechanism proposed on the basis of the known nickel chemistry and three-component coupling reactions proposed for the observed regio- and stereochemistry of products.

Examines the assembly of an alkene and alkyne via a cobalt-catalyzed reductive-coupling mode. Chemical bonds; Molecular structure; Regioselectivity and stereoselectivity of the resulting alkenes; Intermolecular reductive coupling.

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 Col2(PPh3)2/Zn, the reaction of enones and enals with alkynes requires the use of the Col2(dppe)/Zn/Znl2 system. The intramolecular reductive coupling of activated alkenes (enones, enals, acrylates, and acrylonitriles) with alkynes also works efficiently. Further a variety of cyclic lactones and lactams were prepared using this methodology. Possible mechanistic pathways are proposed based on a deuterium-labeling experiment carried out in the presence of D2O. [ABSTRACT FROM AUTHOR]

A highly regio- and stereoselective method for the synthesis of various 2-silylauylboronates 7 from allenes 1 and 2-(dimethylphenylsilanyl)-4,4,5,5-tetramethyl[1,3,2]dioxaborolane (5) catalyzed by palladium complexes and initiated by organic iodides is described. Treatment of monosubstituted aryl and alkylallenes RCH=C=CH2 (1a--m) and 1,1-dimethylallene (1n) with borylsilane 5 in the presence of Pd-(dba)2 (5 mol %) and organic iodide 3a (10 mol %) afforded the corresponding silaboration products 7a--n in moderate to excellent yields. This catalytic silaboration is totally regioselective with the silyl group of 5 adding to the central carbon and the borylgroup to the unsubstituted terminal carbon of allene. Furthermore, the reactions show very high Estereoselectivity with the Z/E ratios lying in the range from &frac199; to &frac793;. In the absence of an organic iodide, silaboration of 1 with 5 still proceeds, but gives products having completely different regiochemistry as that of 7. The silaboration chemistry can be applied to the synthesis of homoallylic alcohols. Treatment of allenes (1) with borylsilane 5 and aldehydes 14 in the presence of Pd(dba)2 (5 mol %) and 3a (10 mol %) at 80 °C in ethyl acetate for 5 h afforded homoallylic alcohols 15a--p in one pot in good to excellent yields, with exceedingly high syn selectivity (>93%). Mechanistic pathways involving an unusual palladium-catalyzed three-component assembling reaction of dirnethylphenylsilyl iodide, allene 1, and borylsilane 5 were proposed to account for these catalytic reactions. [ABSTRACT FROM AUTHOR]

Focuses of an efficient method to a class of 2-acylallylmetal reagents with reference to highly regio and stereoselective acylboration, acylsilation and acylstannation of allenes catalyzed by phosphine-free palladium complexes. Overview of this new efficient method; Account of materials and methods used in the development of this method; Highlights of palladium-catalyzed acylboration of allenes; Features of reactions that were carried out using acyl chloride and integration methods; Overview of palladium-catalyzed acylstannation of allenes; Brief about the mechanistic considerations taken in account during this developmental process.