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We have developed an effective ortho C–H functionalization of arylpyridines and detachable N-pyrimidyl indoles by terminal and internal alkynes using a Re(I) catalyst providing an efficient access to various E-selective alkenylation products. The catalytic reaction is compatible with various aliphatic alkynes, aromatic terminal alkynes and internal alkynes, and structurally different nitrogen heterocycles. Deuterium-labeling experiments indicate that significant deuterium scrambling occurs with the directing groups and acetylenic sp C–H bonds before the migratory insertion.

Reaction mechanisms for the synthesis of indenamines, indenols, and isoquinolinium salts through cobalt- and rhodium-catalysis were investigated using density functional theory calculations. We found that the valence charge of transition metals dramatically influences the reaction pathways. Catalytic reactions involving lower-oxidation-state transition metals (MI/MIII, M = Co and Rh) generally favor a [3 + 2] cyclization pathway, whereas those involving higher oxidation states (MIII/MV) proceed through a [4 + 2] cyclization pathway. A catalytic cycle with novel MIII/MV as a crucial species was successfully revealed for isoquinolinium salts synthesis, in which highly valent MV was encountered not only in the [RhCp*]-catalysis but also in the [CoCp*]-catalysis.

Hydroarylation of bicyclic alkenes has been developed using a low-valent ReI -catalyzed, directing group-assisted C-H bond activation strategy. The addition of sodium acetate significantly improves the reaction efficiency; moreover, bicyclic alkenes such as 7-oxa and aza benzonorbornadienes worked efficiently under this reaction condition. Preliminary mechanistic studies suggest that, after the alkene insertion, the rhenacycle preferentially undergoes protonolysis rather than reductive elimination.

A cobalt-catalyzed C–H/N–H annulation of anilides with allenes to synthesize 1,2-dihydroquinolines is described. The reaction proceeds via a C–H activation, allene insertion, followed by β-hydride elimination and an intramolecular 1,4-addition to a butadiene-group-containing intermediate. Allenes act as a three-carbon source in the present C–H activation strategy.

An Fe(III)-promoted oxidative annulation reaction was developed for the synthesis of 1,2-naphthoquinones. A variety of substituted arylglyoxals and internal alkynes undergo the transformation in the presence of FeCl3 at room temperature to afford the 1,2-naphthoquinone products in good yields in a short reaction time. Interestingly, the products show unusual pseudomigration of the substituent on the arene ring of arylglyoxals. A possible mechanism involving Fe(III)-promoted formation of a vinyl cation from arylglyoxal and alkyne, electrophilic addition of the vinyl cation to the ipso carbon of the aryl group to give a spiral intermediate, and then migration of the keto carbon to the ortho carbon was proposed as key steps and verified using quantum mechanics.

Various substituted indolizidinium, quinolizinium and pyrido[1,2-a]azepinium salts synthesized from benzaldehydes (or α,β-unsaturated aldehydes) and alkyne-amines catalyzed by rhodium complexes via C-H activation are demonstrated. The reaction was carried out under mild reaction conditions using Cu(BF4)2·6H2O as oxidant and anion source and inexpensive oxygen as a co-oxidant. A reaction mechanism involving imine formation followed by an ortho C-H activation, alkyne insertion and reductive elimination via a 7-membered rhodacycle is proposed. The present method has been successfully applied to the synthesis of a natural product, ficuseptine.

A highly chemo- and stereoselective nickel-catalyzed borylative cyclization of 1,6-enynes with bis(pinacolato)diboron is described. Enynes containing an electron-deficient alkene such as a vinyl ketone provided alkenylboronates while enynes containing a terminal alkene gave homoallylic boronates. A plausible mechanism involving a nickelacyclopentene intermediate is proposed. In addition, the resulted alkenyl- or homoallylic boronates can be transformed to the corresponding ketones and alcohols via oxidation. Application to a palladium-catalyzed cross coupling reaction of alkenylboronates with aromatic halides has been demonstrated as well.

A highly regioselective synthesis of pyrido[2,1-a]isoindolium salts from 2-arylpyridines and two equivalents of electron-deficient alkenes catalyzed by rhodium is demonstrated. The reaction was carried out in aqueous medium at 110 °C using inexpensive oxygen as oxidant. Reverse aza-Michael addition of the isoindolium salt occurs when the salt was treated with base to give a β-disubstituted alkene product. A reaction mechanism involving an ortho C–H olefination of 2-arylpyridine by alkene, intramolecular aza-Michael addition, deprotonation at the β-carbon of the alkene fragment followed by another Michael addition to give the final product is proposed.

A novel copper-promoted multiple aza-[4 + 2] cycloaddition reaction of N-methyleneanilines in situ generated from benzylic azide and alkenes afforded quinolinium salts, biquinolinium salts, biquinolines or substituted quinolines depending on the substitution on the phenyl ring of benzylic azide. The reaction of para substituted benzylic azides and 2 equivalents of alkenes afforded the corresponding substituted quinolinium salts, while benzylic azides without a para substituent provided biquinolinium salts. The copper-promoted cycloaddition reaction also allows biquinoline products to be obtained from ortho-substituted benzylic azides. These reactions work well with both terminal and internal alkenes. Unsymmetrical internal alkene reactions proceed with high regioselectivity. The reaction is likely started by Lewis acidic CuII-assisted rearrangement of benzylic azide to N-methyleneaniline, followed by a [4 + 2] cycloaddition with alkene. Detailed mechanistic studies suggest that the biquinoline and biquinolinium salts are likely formed via radical processes.

A method for the synthesis of substituted quinolizinium salts from 2-ethylpyridines and alkynes is demonstrated. The transformation is conveniently achieved using 1 mol % of a Rh(III) catalyst along with an excess amount of copper(II) salt. The reaction gives high product yields with broad substrate scope and functional group tolerance. Detailed mechanistic studies suggest that 2-vinylpyridine is formed in situ from 2-ethylpyridine by a copper-promoted C(sp3)–H hydroxylation, followed by dehydration. Later, a Rh(III)-catalyzed pyridine-directed vinylic C(sp2)–H activation and annulation with alkynes provided the final product.

An efficient o-arylation of pivalamides by aryl iodides via rhodium(III)-catalyzed C–H activation is demonstrated for the first time. Further, the biaryl products can be converted effectively into biologically active phenanthridine and phenanthridinone derivative.

An efficient Co-catalyzed 1,4-addition reaction of alkyl/aryl triflates and tosylates with activated alkenes is described. In this reaction, an air-stable cobalt(ii) complex, a mild reducing agent Zn and a simple proton source (H2O) are used. A radical mechanism for the addition of alkyl tosylates to activated alkenes is likely involved.

A nickel-catalyzed regio- and stereoselective reductive coupling of oxa- and azabicyclic alkenes with activated alkenes and electron-rich alkynes is described. Thus, 7-oxabenzonorbornadienes underwent reductive coupling with various vinyl ketones such as ethyl, methyl, propyl and alpha-methyl-substituted vinyl ketones, in the presence of a nickel(II) iodide (NiI2), zinc (Zn), and water catalyst system in acetonitrile at 50 degrees C for 14 h to afford 2-alkylnaphthalenes in good to excellent yields. Under similar reaction conditions, 7-azabenzonorbornadiene derivatives provided cis-2-alkyl-1,2-dihydro-naphthalene derivatives in high yields. On the other hand, the nickel(II) iodide, tris(4-fluorophenyl)phoshine [P(4-FC6H4)(3)] and zinc catalyst system successfully catalyzed the reductive coupling reaction of electron-rich alkynes, with 7-aza- and 7-oxabenzonorbornadienes to give cis-2-alkenyl-1,2-dihydronaphthalene derivatives in good to excellent yields. In the reaction, a mild reducing agent (zinc) and simple hydrogen source (water) were used.

An efficient method for the synthesis of functionalized vinyl arenes from the reaction of N-methoxybenzamides or N-phenoxyacetamides with vinylstannanes via rhodium(iii)-catalyzed C–H activation is described. The application of the methodology for the synthesis of a natural product thalactamine and a 7-membered ring oxepine are also demonstrated.

Metal-catalyzed annulation reactions to synthesize carbo- and heterocycles have been an attractive field of research for many years. The development of new cyclization reactions utilizing readily available less expensive metal catalyst is one of the important tasks. In this regard, this review summerizes and discusses about nickel- and cobalt-catalyzed [4+2] and [3+2] annulation reactions of ortho-halo substituted imines and alkynes. Nickel complexes under suitable reaction conditions underwent [4+2] annulation to form six-membered isoquinoline (salts) derivatives. However, cobalt complexes afforded aminoindenes via [3+2] annulation reactions. Both reactions proceed through a five membered metallacycle. The regioselective insertion of alkyne containing keto or ester groups into the metallacycle further demonstrates the difference in selectivity of these metal complexes.

An efficient method for the one-pot synthesis of substituted phenanthridinone derivatives from N-methoxybenzamides and aryltriethoxysilanes through rhodium-catalyzed dual C-H bond activation and annulation reactions is described. A double-cycle mechanism is proposed to account for this catalytic reaction. In addition, isotope-labeling studies were performed to understand the intimate mechanism of the reaction.

The reductive coupling of an aryl carbonyl group with an activated alkene to give the corresponding γ-hydroxybutyric acid (GHBA) derivative was achieved in the presence of zinc and ammonia. A board scope of GHBA derivatives could be synthesized under ambient conditions by this method. A mechanism involving a Zn-ketyl radical as the key intermediate is proposed.

The synthesis of highly substituted naphthalenes from allylarenes and alkynes is described. This reaction proceeds via π-coordination of an allylic carbon-carbon double bond to the Pd(II) center and is followed by ortho selective C-H bond activation.

The reaction probably proceeds through a Lewis acidic CuII-assisted rearrangement of benzylic azide to N-methylaniline, followed by a [4+2] cycloaddition with alkene.

A highly diastereoselective method for the synthesis of dihydroepoxybenzofluorenone derivatives from aromatic/vinylic amides and bicyclic alkenes is described. This new transformation proceeds through cobalt-catalyzed C-H activation and intramolecular nucleophilic addition to the amide functional group. Transition-metal-catalyzed C-H activation reactions of secondary amides with alkenes usually lead to [4+2] or [4+1] annulation; to the best of our knowledge, this is the first time that a [3+2] cycloaddition is described in this context. The reaction proceeds under mild conditions and tolerates a wide range of functional groups. Mechanistic studies imply that the C-H bond cleavage may be the rate-limiting step.

Four cobalt-catalyzed oxidative annulation reactions of nitrogen-containing arenes with alkynes proceeds by C-H activation, thus leading to biologically useful quaternary ammonium salts, including pyridoisoquinolinium, cinnolinium, isoquinolinium, and quinolizinium salts, in high yields. The results are comparable to those reactions catalyzed by rhodium and ruthenium complexes. The transformation of the salts into various N-heterocycles has also been demonstrated.

A novel method for the synthesis of functionalized vinyl arenes by reaction of N-methoxybenzamides or N-phenoxyacetamide (XIV) with vinylstannanes via C—H activation is described.

A cobalt-catalyzed reductive coupling of terminal alkynes, RC≡CH, with activated alkenes, R'CH=CH(2), in the presence of zinc and water to give functionalized trans-disubstituted alkenes, RCH=CHCH(2)CH(2)R', is described. A variety of aromatic terminal alkynes underwent reductive coupling with activated alkenes including enones, acrylates, acrylonitrile, and vinyl sulfones in the presence of a CoCl(2)/P(OMe)(3)/Zn catalyst system to afford 1,2-trans-disubstituted alkenes with high regio- and stereoselectivity. Similarly, aliphatic terminal alkynes also efficiently participated in the coupling reaction with acrylates, enones, and vinyl sulfone, in the presence of the CoCl(2)/P(OPh)(3)/Zn system providing a mixture of 1,2-trans- and 1,1-disubstituted functionalized terminal alkene products in high yields. The scope of the reaction was also extended by the coupling of 1,3-enynes and acetylene gas with alkenes. Furthermore, a phosphine-free cobalt-catalyzed reductive coupling of terminal alkynes with enones, affording 1,2-trans-disubstituted alkenes as the major products in a high regioisomeric ratio, is demonstrated. In the reactions, less expensive and air-stable cobalt complexes, a mild reducing agent (Zn) and a simple hydrogen source (water) were used. A possible reaction mechanism involving a cobaltacyclopentene as the key intermediate is proposed.

An efficient method for the synthesis of substituted isoquinolinium salts from benzaldehydes, amines, and alkynes via ruthenium-catalyzed C-H bond activation and annulation in one pot is described.

Pd-catalyzed selective ortho-olefination of arenes assisted by an allylic C-C double bond at room temperature using O(2) as a terminal oxidant is described. A possible mechanism involving the initial coordination of allylic C═C bond to Pd followed by selective o-C-H bond metalation is proposed.

A simple efficient method for the iron(III)-catalyzed synthesis of substituted β-chlorovinyl ketones and α,β-alkynyl ketones from terminal and silyl-substituted alkynes with acid chlorides, respectively, is described. This method features easily available starting materials, a cheap and non-toxic catalyst, simple manipulation and mild reaction conditions. Evidence shows that the catalytic addition of the acid chloride to a terminal alkyne to give (Z)-β-chlorovinyl ketones favours a concerted pathway via a four-membered ring transition state between the two alkyne carbons and the carbon-chloride bond of the acid chloride.

A new catalytic system for β-alkylation of lactic acid with primary alcohols has been developed. In the presence of nickel(II) acetate tetrahydrate [Ni(OAc)2(H2O)4] and base, lactic acid reacts with primary alcohols to afford the corresponding coupled α-hydroxy carboxylic acids in good to excellent yields via a hydrogen transfer process without any hydrogen acceptor or hydrogen donor.

An efficient synthesis of highly substituted isoquinolinium salts from ketimines and alkynes via a Rh(iii)-catalyzed C–H bond activation and annulation reaction is described.

N-Methyl indole reacts with but-2-yn-1-ol in the presence of PtCl(2) in MeOH giving indole derivatives having a substituted 3-oxobutyl group at the 3-position in good yield. Under the reaction conditions, various substituted indoles and substituted propargyl alcohols are successfully involved in the reaction giving the corresponding addition products in good to moderate yields. The catalytic reaction can be further extended to N-phenyl pyrrole. In the present multi-step reaction, PtCl(2) likely plays dual roles: as the catalyst for the rearrangement of propargyl alcohols to the corresponding alkenyl ketones and as the catalyst for the addition of indoles to the alkenyl ketones. Experimental evidence is provided to support the proposed mechanism.

The reaction of benzynes with N-heteroaromatics including quinolines, isoquinolines, and pyridines and various terminal alkynes or ketones with an alpha-hydrogen in the presence of KF and 18-crown-6 in THF at room temperature for 8 h gave various N-arylated 1,2-dihydroheteroaromatics in good to moderate yields. Some of these product structures are found in various naturally occurring and biologically active heterocyclic compounds. The reaction involves an unusual multiple construction of new C--C, C--N, and C--H bonds and the cleavage of a C--H bond in one pot. It is likely that the three-component coupling proceeds through the nucleophilic addition of quinoline to benzyne, which generates a zwitterionic species. The latter then attracts a proton from terminal alkyne (or ketone) to generate an N-arylated quinolinium cation and an acetylide anion. Further reaction of these two ions provides the final substituted 1,2-dihydroquinolines. In the reaction, the terminal alkyne acts first as a proton donor and then as a nucleophile. The application of a three-component coupling reaction product, 1,2-dihydro-2-pyridinyl alkyne in a stereospecific [4+2] Diels-Alder cycloaddition reaction with N-phenyl maleimide to give an isoquinuclidine derivative, an important core present in various natural products, is demonstrated.

Described herein is a convenient and highly regioselective synthesis of substituted isoquinoline derivatives from various aromatic ketoximes and alkynes via a one-pot, rhodium-catalyzed C-H bond activation. In addition, tetrahydroquinoline derivatives are formed in good yields from 2-arylidene-1-cyclohexanone oximes possessing an exocyclic double bond and from tetrahydroxanthone oximes. A possible mechanism is proposed that involves chelation-assisted C-H activation via oxidative addition of Rh(I) to an ortho-C-H bond, insertion of the alkyne, reductive elimination, intramolecular electrocyclization, and aromatization. This mechanism is supported by isolation of the ortho-alkenylation products 7p and 7q. Also described herein is an example of an iridium-catalyzed activation of an sp(3) C-H bond.

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 with alkynes requires the use of the CoI2(dppe)/Zn/ZnI2 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.

Highly substituted pyridinium salts are synthesized via a multicomponent reaction of vinyl ketones/aldehydes, amines, and alkynes.

This efficient reaction which proceeds regioselectively at the sterically more congested C—H bond can be scaled up.

Rh-catalyzed reaction of N-hydroxybenzamidines with an excess of internal alkynes and an excess of Cu(OAc)2 as the oxidant is described to produce polyhetarenes in good yields.

[Reaction: see text]. An efficient method for the synthesis of cis-2-alkyl- or allyl-1,2-dihydronaphthalenes via a nickel-catalyzed highly regio- and stereoselective ring-opening addition of alkyl- or allylzirconium reagents to 7-oxabenzonorbornadienes is described. Treatment of 7-oxabenzonorbornadienes 1a-c with various alkylzirconium reagents 2a-j (Cp2ZrClCH2CH2R: R = tert-butyl, n-butyl, n-pentyl, -(CH2)3CH=C(CH3)2, -SiMe3, -CH2SiMe3, -(CH2)3Br, cyclopentyl, cyclohexyl, and benzyl) in the presence of NiBr2(dppe) and Zn powder in dry THF at 50 degrees C afforded the corresponding cis-2-alkyl-1,2-dihydronaphthalene derivatives 3a-m in good yields. In addition, allyl zirconium reagents 4a-c also underwent ring-opening reactions with 1a and 1c to give 5a-d in very good yields. The alkylative ring-opening products from 7-oxabenzonorbornadiene can be further converted to naphthalene derivatives 6a-c, via an acid-mediated dehydration, in good to excellent yields. A possible mechanism for the present catalytic reaction was proposed.

A highly regio- and stereoselective ring-opening addition of alkenylzirconium reagents to bicyclic olefins catalyzed by nickel complexes was described. Treatment of 7-oxa- and 7-azabenzonorbornadienes (1a-e) with various terminal alkenylzirconium reagents 2a-f (Cp(2)ZrClCH=CHR; R = t-Bu, n-Pr, n-Oct, 1-cyclohexenyl, SiMe(3), and Ph) in the presence of Ni(PPh(3))(2)Cl(2) and Zn powder (or a combination of ZnCl(2) and NEt(3)) in dry THF at 50 degrees C afforded the corresponding cis-2-alkenyl-1,2-dihydronaphthalene derivatives 3a-l in moderate to excellent yields. Under similar reaction conditions, internal alkenylzirconium reagents 2g,h (Cp(2)ZrClCR=CHR: R = Et and n-Pr) also undergo ring-opening addition to oxanorbornadienes 1a and 1d to give cis-2-alkenyl-1,2-dihydronaphthalene derivatives 4a-c in good yields. Possible pathways involving the transfer of alkenyl group in the alkenylzirconium reagent to the Ni(II) center followed by migration of the alkenyl group from the Ni(II) center to the carbon-carbon double bond of 7-oxanorbornadiene or the reaction of 7-oxanorbornadiene with Ni(0) to form a Ni(II)-pi-allyl prior to the transfer of the alkenyl group as key steps for the catalytic reaction were proposed and discussed.

In the presence of CoX 2 (PPh 3 ) 2 /3 PPh 3 and zinc metal conjugated alkenes (CH 2 CHCOOR, CH 2 CHCN, CH 2 CHSO 2 Ph and CH 2 CHCONEt 2 ) undergo reductive tail-to-tail dimerization to yield the corresponding saturated linear products. Under similar reaction conditions, vinylarenes (ArCHCH 2 ) give stereoselective head-to-tail dimerization products, trans -1,3-diarylbut-1-ene, in good to excellent yields.

In the presence of Ni(dppe)Br(2) and Zn powder in acetonitrile at 80 degrees C, oxa-bicyclic olefins undergo cyclization with o-iodobenzoate and with beta-iodo-(Z)-propenoates to give the benzocoumarin derivatives in moderate to good yields. This methodology offers a simple efficient way for the synthesis of structurally complicate coumarins in one pot. [reaction: see text]

7-Oxabenzonorbornadienes derivatives la-d underwent reductive coupling with alkyl propiolates CH 3 C≡CCO 2 CH 3 (2 a), PhC≡CCO 2 Et (2b), CH 3 (CH 2 ) 3 C≡CCO 2 CH 3 (2 c), CH 3 (CH 2 ) 4 C≡CCO 2 CH 3 (2d), TMSC≡ CCO 2 Et (2e), (CH 3 ) 3 C≡CCO 2 CH 3 (2 f) and HC≡CCO 2 Et (2g) in the presence of [NiBr 2 (dppe)] (dppe = Ph 2 PCH 2 CH 2 PPh 2 ), H 2 O and zinc powder in acetonitrile at room temperature to afford the corresponding 2-alkenyl-1,2-dihydronapthalen-1-ol derivatives 3 a - n with remarkable regio- and diastereoselectivity in good to excellent yields. Similarly, the reaction of 7-azabenzonorbornadienes derivative 1e with propiolates 2a, b and d proceeded smoothly to afford reductive coupling products 2-alkenyl-1,2-dihydronapthalene carbamates 3o-p in good yields with high regio- and stereoselectivity. This nickel-catalyzed reductive coupling can be further extended to the reaction of 7-oxabenzonorbornene derivatives. Thus, 5,6-di(methoxymethyl)-7-oxabicydo[2.2.1]hept-2-ene (4) reacted with 2a and 2d to furnish cyclohexenol derivatives bearing four cis substituents 5 a and b in 81 and 84% yield, respectively. In contrast to the results of 4 with 2, the reaction of dimethyl 7-oxabicyclo[2.2.1]-hept-5-ene-2,3-dicarboxylate (6) with propiolates 2a-d afforded the corresponding reductive coupling/cyclization products, bicyclo[3.2.1]γ-lactones 7a-d in good yields. The reaction provides a convenient one-pot synthesis of γ-lactones with remarkably high regio- and stereoselectivity.

An efficient method for the preparation of various monosubstituted arylallenes, disubstituted allenes and alkenylallenes via palladium-catalyzed coupling of allenylstannanes with aryl iodides or alkenyl iodides is described. The coupling reaction was carried out in the presence of Pd(PPh 3 ) 4 and LiCl using DMF as solvent. The possible role of LiCl in this coupling process is discussed based on the 119 Sn NMR studies.

In this article, new metal-mediated cyclization and reductive coupling reactions of bicyclic olefins with alkynes are described. Oxabicyclic alkenes undergo cyclization with alkyl propiolates at 80 C catalyzed by nickel complexes to give benzocoumarin derivatives in high yields. The reaction of bicyclic alkenes (oxa- and azacyclic alkenes) with alkyl propiolates at room temperature in the presence of the same nickel complex gave 1,2-dihydro-napthelene derivatives in good-to-excellent yields. This reductive coupling reaction proceeds under very mild conditions in complete regio- and stereoselective fashion. A mechanism to account for the coumarin formation and the reductive coupling is proposed.

A CoI(2)/(R)-BINAP, Zn, ZnI(2), H(2)O system efficiently catalyzes the intermolecular asymmetric reductive coupling of alkynes with cyclic enones to afford highly regio- and enantioselective β-alkenyl cyclic ketones. A possible mechanism that involves the formation of a cobaltacyclopentene intermediate from the alkyne and cyclic enone is proposed.

A nickel-catalyzed regio- and stereoselective reductive coupling of oxa- and azabicyclic alkenes with activated alkenes and electron-rich alkynes is described. Thus, 7-oxabenzonorbornadienes underwent reductive coupling with various vinyl ketones such as ethyl, methyl, propyl and alpha-methyl-substituted vinyl ketones, in the presence of a nickel(II) iodide (NiI2), zinc (Zn), and water catalyst system in acetonitrile at 50 degrees C for 14 h to afford 2-alkylnaphthalenes in good to excellent yields. Under similar reaction conditions, 7-azabenzonorbornadiene derivatives provided cis-2-alkyl-1,2-dihydro-naphthalene derivatives in high yields. On the other hand, the nickel(II) iodide, tris(4-fluorophenyl)phoshine [P(4-FC6H4)(3)] and zinc catalyst system successfully catalyzed the reductive coupling reaction of electron-rich alkynes, with 7-aza- and 7-oxabenzonorbornadienes to give cis-2-alkenyl-1,2-dihydronaphthalene derivatives in good to excellent yields. In the reaction, a mild reducing agent (zinc) and simple hydrogen source (water) were used.

A nickel-catalyzed, highly regioselective conjugate addition of boronic acids to dienones to form 1,4-addition products with an all-carbon quaternary center is described.

The highly regioselective synthesis of unprotected indoles involves the reaction of the hydrochloride substrates with diethyl ketone to form hydrazones.

A nickel-catalyzed highly regioselective 1,4-addition reaction of boronic acids to dienones to form products with an all-carbon quaternary center is described. The 3-alkenyl group of dienones is the key for the reaction to proceed smoothly. A mechanism involving the coordination of the dienyl group to the nickel center is proposed.