Cycloaddition 3 + 1 + 1-, nickel catalyse

The nickel-catalysed 3 + 1 + 1-cycloaddition of alkenyl Fischer carbene complexes with methylenecyclopropanes produced the methylenecyclopentanone in high yields.169 The nickel-catalysed three-component 3 + 2 + 2-cocyclization of ethyl cyclopropylide-neacetate with two alkynes gave cycloheptadienes in good yields and high chemo- and regio-selectivity.170... 

A nickel-catalysed [4-1-2] cycloaddition of formamides with allgmes through double C-H activation as shown in Scheme 14.67 was also carried out in the presence of AlMes, forming dihydropyridones along with a,p-unsaturated amides as side products. The side products were formed via insertion of alkynes into the C(0)-H bond. Use of PtBus as a ligand is crucial for the success of the reaction. If an unsymmetrical internal all ne is used, a mixture of regioisomers of dihydropyridones was obtained. ... 

The nickel-catalysed 2 + 2 + 2-cycloaddition of a 3-methyl-2-pyridyl aldimines with alkynes produced 1,2-dihydropyridine adducts in good yields. A key step in this transformation is the formation of aza-nickelacycle intermediates. The iron-catalysed 2 + 2 + 2-cycloadditions of alkyne nitriles with alkynes, in the presence of pyridyl bisimine ligands (95), formed substituted pyridines in good yields. The nickel-catalysed 2 + 2 + 2-cycloadditions of diynes and cyanamides have been investigated. The reactions have been shown to be regioselective, and cycloadducts are produced in good to excellent yields. ... 

A nickel-catalysed cycloaddition has been reported where anthranilic acid derivatives react with alkynes to give substituted indoles initial oxidative addition of Ni(0) to an ester moiety allows intermolecular addition to alkynes via decarbonylation and [l,3]-acyl migration (Scheme 132). 

In 1987, Tsuji reported for the first time the racemic palladium-catalysed 1,3-dipolar cycloaddition of vinylcyclopropanes with aryl isocyanates to give the corresponding 5-lactams. ° In 2008, Johnson et al. developed racemic palladium-catalysed cycloadditions of vinylcyclopropanes with aldehydes for the formation of tetrahydrofurans. Inspired by these pioneering results, Kura-hashi and Matsubara have recently developed nickel-catalysed 1,3-dipolar cycloaddition of vinylcyclopropanes with imines to give regioselectively the corresponding substituted pyrrolidine derivatives. As shown in Scheme 1.15,... 

In the last decade, several excellent results were also published in the area of enantioselective nickel-catalysed Diels-Alder cycloadditions. Among them, the reactions of cyclopentadiene with 3-alkenoyloxazolidin-2-ones induced by (i )-BINIM-2QN provided cycloadducts in up to >99% yield, >98% de, and 96% ee. Another excellent result was achieved by using a chiral iV,iV -oxide-derived nickel catalyst in Diels-Alder cycloadditions of 3-vinylindoles with methyleneindolinones for the construction of chiral spiro[carbazole-oxindoles] in up to 97% yield, >98% de, and 98% ee. Moreover, the use of the chiral DBFOX-Ph ligand has allowed an inverse-electron-demand Diels-Alder reaction of a range of Af-sulfonyl-l-azadienes with vinyl ethers to be achieved, providing highly functionalised piperidines in up to 75% yield, 96% de, and 92% ee. 

Earlier, Kurahashi and Matsubara described regio- and enantioselective nickel-catalysed decarbonylative formal cycloadditions of phthalic anhydrides with allenes to give in a single step the corresponding chiral 5-lac-tones. The process represented an unprecedented insertion reaction of a carbon-carbon double bond into a carbon-oxygen bond. It was performed in the presence of a chiral nickel catalyst generated in situ from Ni(cod)2 and (5,5)-i-Pr-FOXAP in pyridine at reflux. The chiral 5-lactones were achieved in both moderate to good yields (64-73%) and with enantioselectivities of 59-81% ee, as shown in Scheme 4.16. Better yields (73-90%) and enantioselectivities... 

Scheme 3.5 Domino carbonyl ylide formation-l,3-dipolar cycloaddition reaction catalysed by a combination of rhodium catalysis and chiral nickel catalysis.

A catalytic asymmetric cycloaddition reaction between norbomadiene and methylenecyclopropane can also be achieved in the presence of a [Ni(cod)2]-(—)-benzylmethylphenylphosphine catalyst to give the cycloadduct (72) in an optically active form. This reaction may proceed via a metallocyclopentane intermediate. The reactions of methylenecyclopropane with [Ni(cod)2l-phosphine systems do not appear to involve cleavage of the three-membered ring. However, the bis(acrylonitrile)nickel-catalysed cycloaddition reaction of methylenecyclopropane with methyl acrylate, which yields 3-methoxy-carbonylmethylenecyclopentane (73), does involve C—C bond cleavage. Reaction with the deuterium-substituted compound CHD=CDC02Me gives the cyclopentane derivative (74). An intermediate of the type (75) may be involved in this reaction. 

A variety of oxetanes are available commercially, and finding appropriate handles (amines, acids, alcohol, etc.) is not difficult. Traditional methods of oxetane synthesis, such as Williamson ether synthesis and [2 + 2] cycloadditions, have been extensively reviewed. Of more interest in the rapid expansion of a monomer collection is the functionalisation of simple oxetanes. For example, atyl oxetanes have been prepared by the nickel catalysed Suzuki coupling of 3-iodooxetane (Scheme 18.20). ... 

The enantioselective intramolecular formal 2+4-cycloaddition of acrylates and a, -unsaturated imines (99) catalysed by chiral phosphines (100), derived from amino acids, produced A-heterocycles (101) (Scheme 31). Chiral dirhodium(II) carboxamidates (102) catalysed the hetero-Diels-Alder reactions between 2-aza-3-silyloxy-l,3-butadienes and aldehydes to yield all cw-substituted l,3-oxazinan-4-ones in high yields and high enantioselectivity (98% ee)P The nickel-catalysed 4 + 2-cycloaddition of a, -unsaturated oximes with alkynes yielded 2,3,4,6-tetrasubstituted pyridine derivatives. The reaction of isoquinoline, an activated alkyne, and 4-oxo-4//-l-benzopyran-3-carboxaldehyde (103), in ionic solvents, produced 9a//,15//-benzo[a][l]benzopyrano[2,3-/t]quinolizine derivatives (105) via the zwitterion (104) selectively and in good yields (Scheme 32).The Diels-Alder cycloaddition of ethyl 3-(tetrazol-5-yl)-l,2-diaza-l,3-butadiene-l-carboxylates with -rich heterocycles, nucleophilic olefins, and cumulenes formed 3-tetrazolyl-l,4,5,6-tetrahydropyridazines regioselectively. The silver-catalysed formal inverse-electron-demand Diels-Alder... 

The [2-I-2-I-2] cycloaddition reaction of diynes 40 and carbon dioxide 41 were successfully catalysed by a NHC-nickel (Scheme 5.12) [15]. The NHC-Ni complex was prepared in situ from [NiCCOD) ] and two equivalents of carbene. Pyrones 42 were obtained in excellent yields at atmospheric pressure of CO and mild reaction conditions. 

Pyridine compounds 45 can also be produced by the NHC-Ni catalysed cycloaddition between nitriles 43 and diynes 44 (Scheme 5.13) [16]. The SIPr carbene was found to be the best ligand for the nickel complex in this reaction. The reaction required mild reaction conditions and low catalyst loadings, as in the case of cycloaddition of carbon dioxide. In addition to tethered aUcynes (i.e. diynes), pyridines were prepared from a 3-component coupling reaction with 43 and 3-hexyne 23 (Scheme 5.13). The reaction of diynes 44 and nitriles 43 was also catalysed by a combination of [Ni(COD)J, NHC salts and "BuLi, which generates the NHC-Ni catalyst in situ. The pyridines 45 were obtained with comparable... 

Nickel(O) complexes catalyse [2+2+2] cycloaddition. Catalytic asymmetric synthesis of isoquinoline derivative 134 is possible based on enantiotopic group-selective formation of the nickelacyclopentadiene 133 from 132 using the Ni(0) complex coordinated by a chiral ligand under acetylene atmosphere [56]. 

An important achievement is the synthesis of optically active fusicoccane, in which the key reaction is cyclization of the bis aldehyde (69). 118 Ring closure of the cobalt complex propargyl derivative (70), involving reaction via a cobalt stabilized carbocation gives access to eight-membered rings117 which are also the product of the nickel(0) catalysed [4+4]cycloaddition of the tetraene (71).118... 

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