Highly Regio- and Stereoselective Cocyclotrimerization and Linear Cotrimerization of α,β-Unsaturated Carbonyl Compounds with Alkynes Catalyzed by Nickel Complexes

Abstract

Cyclic enones 2-cyclohexen-1-one (1a), 4,4-dimethyl-2-cyclohexen-1-one (1b), 2-cyclopenten-1-one (1c), and 2-cyclohepten-1-one (1d) react with octa-1,7-diyne (2) in THF in the presence of Ni(PPh(3))(2)I(2), ZnI(2), and Zn powder at 62 degrees C to give [2 + 2 + 2] cycloaddition-dehydrogenation products 3a-d in 32-80% yields. alpha,beta-Unsaturated lactone 5a (5,6-dihydro-2H-pyran-2-one) undergoes [2 + 2 + 2] cycloaddition with 2 to give both the corresponding cyclohexadiene product 6 (29%) and dehydrogenation product 7 (39%). Under similar reaction conditions, 3-buten-2-one reacts with 2 and various substituted hepta-1,6-diynes 9a-c to give [2 + 2 + 2] cycloaddition-dehydrogenation products 11a-d in 68-80% yields. Diphenylacetylene also reacts with 1a-d, 5a, and 2(5H)-furanone (5b) to afford the corresponding [2 + 2 + 2] cocyclotrimerization products 13a-d and 14a-b. No dehydrogenation of products 13 and 14 was observed under the reaction and workup conditions. The reactions of acrylates with alkynes catalyzed by nickel complexes give products that depend greatly on the reaction conditions. Treating ethyl acrylate (15a) with 1-phenyl-1-propyne (16) in the presence of Ni(PPh(3))(2)Cl(2) and Zn at 90 degrees C in toluene affords cocyclotrimerization product 19aas the major product (54% yield). However, treatment of CH(2)CHCOOR (R = Et and t-Bu) with mono alkynes 16 and 12 in the presence of Ni(PPh(3))(2)X(2) (X = Cl and I) and Zn powder in toluene at 60 degrees C affords the corresponding conjugated trienes 17a-c in 82-92% yields. The MS data of 17firmly support an adduct of two molecules of alkyne and a molecule of acrylate. Similarly, the reaction of 15a with octa-1,7-diyne in the presence of Ni(PPh(3))(2)I(2), ZnI(2), and zinc gives triene derivative 21 in 68% yield. NOE and X-ray results indicate that in these trienes the substituents from each alkyne and alkene moiety are cis to each other. The unique stereoselectivity can be attributed to the exclusive formation of seven-membered nickelacycloheptadiene intermediate 25during the catalytic reaction.

Cobalt‐Mediated Linear 2:1 Co‐oligomerization of Alkynes with Enol Ethers to Give 1‐Alkoxy‐1,3,5‐Trienes: A Missing Mode of Reactivity

“…To the best of our knowledge, the first example of such a reaction was reported by Cairns and co-workers in 1952. [3] They found that a mixture of [Ni(CO) 4 ] and PA C H T U N G T R E N N U N G (C 6 H 5 ) 3 catalyzed the addition of acetylene to acrylic compounds to give heptatrienoic acid derivatives. In 1999, Cheng extended this reaction to substituted alkynes by employing mixtures of [Ni-A C H T U N G T R E N N U N G (PR 3 ) 2 X 2 ] and Zn.…”

“…In 1999, Cheng extended this reaction to substituted alkynes by employing mixtures of [Ni-A C H T U N G T R E N N U N G (PR 3 ) 2 X 2 ] and Zn. [4] Ruthenium entered the scene in 1998 when Yi discovered that acetylene and acrylonitrile transAbstract: A variety of 1,6-heptadiynes and certain borylalkynes co-oligomerize with enol ethers in the presence of [CpCoA C H T U N G T R E N N U N G (C 2 H 4 ) 2 ] (Cp= cyclopentadienyl) to furnish the hitherto elusive acyclic 2:1 products, 1,3,5-trien-1-ol ethers, in preference to or in competition with the alternative pathway that leads to the standard [2 + 2 + 2] cycloadducts, 5-alkoxy-1,3-cyclohexadienes. Minor variations, such as lengthening the diyne tether, cause reversion to the standard mechanism.…”

Synthesis of 1-indanones with a broad range of biological activity

“…Cheng et al have obtained 1-indanone 285 from octa-1,7-diyne ( 282 ) and cyclopentenone 239 as a result of Ni-complex-catalyzed [2 + 2 + 2] cyclotrimerization proceeding via the intermediate 283 [110] (Scheme 79). The dimer 284 of the starting dialkyne has also been obtained.…”

Synthesis, crystal structure, thermal and theoretical studies of bis(N-ethyl-N-phenyldithiocarbamato) Ni(II) and (N-ethyl-N-phenyldithiocarbamato) (isothiocyanato) (triphenylphosphine) Ni(II)

“…The complexes displayed interesting electrochemical properties and higher antimicrobial activity compared with the commercially available antibiotics, and have found application in various areas such as catalysts in crosscoupling reactions and medicine. [8][9][10][11] They are also used as effective light stabilizers for olefins, 12 and recently as precursors for the preparation of nanoparticles. 13 Ni(II) complexes do not stabilize their geometries effectively under various chemical environments.…”