Cyclization Of Diynes Research Articles

Theoretical Study on Ruthenium-Catalyzed Hydrocarbamoylative Cyclization of 1,6-Diyne with Dimethylformamide

The reaction mechanism of ruthenium-catalyzed hydrocarbamoylative cyclization of diynes with dimethylformamide was studied by computation of model complexes using the density functional theory (DFT) method. Based on the DFT calculations, a plausible mechanism is proposed, involving oxidative coupling of a diyne catalyzed by CpRuH (Cp = η5-C5H5), C–H bond-forming reductive elimination, dimethylformamide insertion, and β-H elimination.

Furan Is Superior to Thiophene: A Furan-Cored AIEgen with Remarkable Chromism and OLED Performance.

Furan‐cored AIEgen namely tetraphenylethylene‐furan (TPE‐F) is developed by diyne cyclization and its fluorescent and chemical properties are investigated and compared with its thiophene analogue. Results show that furan is superior to thiophene in terms of fluorescence, chromism, and charge transport. The mechanism of chromism of TPE‐F is investigated and its efficient solid‐state photoluminescence and good charge‐transporting property enable it to serve as light‐emitting material for the construction of electroluminescence devices with excellent performance. This work not only demonstrates an efficient strategy for constructing furan‐cored AIEgens but also indicates that they are promising as advanced optoelectronic materials.

New Pathways for the Dual Gold-Catalyzed Cyclization of Diynes.

The reaction of thiophene-based diynes with dual-activation gold catalysts can provide cyclobutene derivatives or different polycycles by selective C-H insertion reactions. Also, the first σ,π-digold diyne complex was obtained in a stoichiometric reaction, providing insight into the dual activation mechanism. The new products were unambiguously identified by X-ray single-crystal structure analysis.

ChemInform Abstract: Eco‐Friendly Synthesis of Pyridines via Rhodium‐Catalyzed Cyclization of Diynes with Oximes.

AbstractA new route for the preparation of title compounds such as (III) and (V) via [2+2+2] cycloaddition of various diynes (I) and oximes using [Rh(nbd)2]BF4/MeO‐Bipheb as catalyst.

ChemInform Abstract: Synthesis of Highly Substituted N‐(Furan‐3‐ylmethylene)benzenesulfonamides by a Gold(I)‐Catalyzed Oxidation/1,2‐Alkynyl Migration/Cyclization Cascade.

AbstractA rarely observed 1,2‐alkynyl migration occurs in the Au‐catalyzed cyclization of diynes to give tosylimine furans.

ChemInform Abstract: Rhodium‐Catalyzed Cyclization of Diynes with Nitrones: A Formal [2 + 2 + 5] Approach to Bridged Eight‐Membered Heterocycles.

N-aryl-substituted nitrones were employed as five-atom coupling partners in the rhodium-catalyzed cyclization with diynes. In this reaction, the nitrone moiety served as a directing group for the catalytic C-H activation of the N-aryl ring. This formal [2+2+5] approach allows rapid access to bridged eight-membered heterocycles with broad substrate scope. The results of this study may provide new insight into the chemistry of nitrones and find applications in the synthesis of other heterocycles.

Eco-friendly synthesis of pyridines via rhodium-catalyzed cyclization of diynes with oximes

We describe a new route for the synthesis of pyridines via [2 + 2 + 2] cycloaddition of diynes and oximes catalyzed by Rh(NBD)2BF4/MeO-Biphep using ethanol as an alternative reaction medium, affording the desired pyridine derivatives in yields of up to 93%.

Ni(NHC)]-catalyzed cycloaddition of diynes and tropone: apparent enone cycloaddition involving an 8π insertion.

A Ni/N-heterocyclic carbene catalyst couples diynes to the C(α)–C(β) double bond of tropone, a type of reaction that is unprecedented for metal-catalyzed cycloadditions with aromatic tropone. Many different diynes were efficiently coupled to afford [5–6–7] fused tricyclic products, while [5–7–6] fused tricyclic compounds were obtained as minor byproducts in a few cases. The reaction has broad substrate scope and tolerates a wide range of functional groups, and excellent regioselectivity is found with unsymmetrical diynes. Theoretical calculations show that the apparent enone cycloaddition occurs through a distinctive 8π insertion of tropone. The initial intramolecular oxidative cyclization of diyne produces the nickelacyclopentadiene intermediate. This intermediate undergoes an 8π insertion of tropone, and subsequent reductive elimination generates the [5–6–7] fused tricyclic product. This initial product undergoes two competing isomerizations, leading to the observed [5–6–7] and [5–7–6] fused tricyclic products.

Selenium halide-induced bridge formation in [2.2]paracyclophanes.

An addition/elimination sequence of selenium halides to pseudo-geminally bis(acetylene) substituted [2.2]paracyclophanes leads to new bridges with an endo-exo-diene substructure. The reactions have been found to be sensitive to the substitution of the ethynyl group. The formation of dienes with a zig-zag configuration is related to that observed for non-conjugated cyclic diynes of medium ring size.

Rhodium-catalyzed cyclization of diynes with nitrones: a formal [2+2+5] approach to bridged eight-membered heterocycles.

N-aryl-substituted nitrones were employed as five-atom coupling partners in the rhodium-catalyzed cyclization with diynes. In this reaction, the nitrone moiety served as a directing group for the catalytic C-H activation of the N-aryl ring. This formal [2+2+5] approach allows rapid access to bridged eight-membered heterocycles with broad substrate scope. The results of this study may provide new insight into the chemistry of nitrones and find applications in the synthesis of other heterocycles.

Rhodium‐Catalyzed Cyclization of Diynes with Nitrones: A Formal [2+2+5] Approach to Bridged Eight‐Membered Heterocycles

AbstractN‐aryl‐substituted nitrones were employed as five‐atom coupling partners in the rhodium‐catalyzed cyclization with diynes. In this reaction, the nitrone moiety served as a directing group for the catalytic CH activation of the N‐aryl ring. This formal [2+2+5] approach allows rapid access to bridged eight‐membered heterocycles with broad substrate scope. The results of this study may provide new insight into the chemistry of nitrones and find applications in the synthesis of other heterocycles.

ChemInform Abstract: Sequential Catalysis for Stereoselective Synthesis of Complex Polyketides

AbstractReview: 111 refs.

ChemInform Abstract: Gold‐Catalyzed Cyclization of Diynes: Controlling the Mode of 5‐endo versus 6‐endo Cyclization — An Experimental and Theoretical Study by Utilizing Diethynylthiophenes.

AbstractA dual‐gold catalyzed cyclization of 3,4‐diethynylthiophenes generating new heteroaromatic compounds bearing five‐membered annulated ring systems is reported.

ChemInform Abstract: 1,6‐Carbene Transfer: Gold‐Catalyzed Oxidative Diyne Cyclizations.

AbstractIn the presence of a gold catalyst an unprecedented oxidative cyclization of diynes takes place.

Sequential catalysis for stereoselective synthesis of complex polyketides

This review presents recent advances in sequential catalytic methods developed in our group for the rapid and stereoselective synthesis of key structural features of complex polyketides. These include a novel domino reaction, based on a combination of a nucleophilic addition and a Tsuji-Trost reaction, an innovative sequence relying on an oxidative diyne cyclization and regioselective opening, as well as sequential cross coupling strategies. The design and scope of these methods are discussed and applications in complex target syntheses presented.

1,6-Carbene Transfer: Gold-Catalyzed Oxidative Diyne Cyclizations

In the presence of a gold catalyst an unprecedented oxidative cyclization of diynes takes place. The reaction cascade is initiated by an oxygen transfer from a N-oxide onto a gold-activated alkyne. The formed α-oxo carbene is transferred across the second alkyne yielding a stabilized vinyl carbene/cation. Alkyl migration or sp(3)-CH insertion then terminates the catalytic cycle by formation of highly substituted functionalized indenones. A 1,6-carbene shift could be supported by the oxidation of the vinyl carbene. This protocol represents an attractive alternative to procedures which are based on the metal-catalyzed decomposition of hazardous, not easily accessible, diazo compounds.

Enantioselective Synthesis of Planar‐Chiral Carba‐Paracyclophanes: Rhodium‐Catalyzed [2+2+2] Cycloaddition of Cyclic Diynes with Terminal Monoynes

Enantioselective Synthesis of Planar‐Chiral Carba‐Paracyclophanes: Rhodium‐Catalyzed [2+2+2] Cycloaddition of Cyclic Diynes with Terminal Monoynes

Enantioselective Synthesis of Planar‐Chiral Carba‐Paracyclophanes: Rhodium‐Catalyzed [2+2+2] Cycloaddition of Cyclic Diynes with Terminal Monoynes

Eben einfach chiral: Carba[10]–[12]Paracyclophane wurden in Ausbeuten bis 91 % und mit bis zu 93 % ee durch die [2+2+2]-Cycloaddition von cyclischen Diinen mit terminalen Monoinen in Gegenwart eines kationischen Rhodium(I)/(S,S)-bdpp-Katalysators erhalten, wobei hohe Substratkonzentrationen eingesetzt wurden. nbd=2,5-Norbornadien, Ns=p-Nitrobenzolsulfonyl, Ts=4-Toluolsulfonyl.

ChemInform Abstract: Palladium‐Catalyzed Cyanation of Nonactivated Alkynes; Development of Cyanopalladation and Its Application to Cyclization and Cycloaddition Reactions

AbstractReview: ca. 50 refs.

ChemInform Abstract: Bromine‐Mediated Cyclization of 1,4‐Diaryl Buta‐1,3‐diyne to 1,2,3‐Tribromo‐4‐aryl Naphthalene.

AbstractThe intramolecular and regioselective cyclization of diynes (IIa)‐(IIe) into naphthalene motifs (III) proceeds under mild conditions by 6‐endo‐dig electrophilic cyclization.