So something like sodium amide, so this in nh2 minus over here came from na plus nh2 minus, so sodium amide, which is a very strong base. A number of new alkynes derivatives are now available through. Us6225500b1 us08816,709 us81670997a us6225500b1 us 6225500 b1 us6225500 b1 us 6225500b1 us 81670997 a us81670997 a us 81670997a us 6225500 b1 us6225500 b1 us 6225500b1 authority us united states prior art keywords catalyst ml cyclotrimerization ch chem prior art date 19960320 legal status the legal status is an assumption and is not a legal conclusion. Iron catalysis for the cyclotrimerization of alkynes. Additions are the most common reactions using alkenes and alkynes addition to. Many variations have been developed including cyclization of mixtures of alkynes and alkenes as well as alkynes and nitriles.
Ethyne is prepared on large scale by the reaction of water on calcium carbide. A proton source like h2o must be added to regenerate the terminal alkyne. This represents the second example of such reactions facilitated by a nonmetallic catalyst, as. In comparison with the nicatalysts reported in literature, complex ptol 1 is a competitive catalyst in terms of activity and regioselectivity from 90. Regioselective cyclotrimerization of terminal alkynes using a digermyne. Pdf construction of fused heterocycles by metalmediated 2. Ethyne can also be prepared on industrial scale by pyrolysis of methane at very high temperature of about 1800 k. Pdf the catalytic activity of nickel complexes in hydrophosphination involving.
Internal alkynes such as 3hexyne and 4octyne were converted. Number the chain from the end closest to the triple bond. The process is of historic interest as well as being applicable to organic synthesis. The answer to the puzzle of parallel reaction pathways.
Mechanism for the cyclotrimerization of alkynes and related. Cyclotrimerization of alkynes catalyzed by the naphthalene. Cyclotrimerization of monosubstituted alkynes in the. Cherkasova for providing the rhodium complexes, also to n. Alkynes are traditionally known as acetylenes, although the name acetylene also refers specifically to c 2 h 2, known. A crucial aspect of the cpco alkyne cyclotrimerization mechanism in organic solvents is the dissociative formation of. The key intermediate in all cases is a triplet cobaltacyclopentadiene obtained by oxidative coupling of the. The simplest alkyne, ethyne also known as acetylene, has two carbon atoms and the.
Intramolecular cyclotrimerization of triynes catalyzed by n. Pdf construction of fused heterocycles by metalmediated. Abstract abstracttreatment of 60fullerene with hccco2r in the presence of pcy3 at ambient temperature affords a cyclotrimerization product r et, 1. Regioselective cyclotrimerization of terminal alkynes. This complex represents a convenient selfsupported nickel0 catalyst with no need for additional ligands and reducing agent.
Cationic rhodiumimodified binap complexes are effective catalysts for highly regioselective intermolecular cyclotrimerization of terminal alkynes and highly chemo and regioselective intermolecular cocyclotrimerization of diethyl acetylenedicarboxylate dead and terminal alkynes. Beyond a small number of standout examples, many reports in the literature focus on the use of simple nickel salts. Method for the cyclotrimerization of alkynes in aqueous solutions download pdf info publication number us5760266a. Cyclooligomerization of dienes cyclodimerization and cyclotrimerization of 1,3. Si2ome6 also catalyzes the cyclotrimerization of alkynes, but with lower conversions yields. Intramolecular cyclotrimerization of triynes catalyzed by. A complete catalytic cycle for the cyclotrimerization of acetylene with the.
Acetylene itself is formed from the reaction of the inorganic compound calcium carbide with water. Reaction in which halogen is introduced into a molecule 3 hydration. The diphosphine ketone supported nickel complex ptoll1nibpi ptol1. Cyclotrimerization of alkynes to yield substituted benzenes is a possible method for their synthesis.
The reaction operates under very mild conditions vis light, room temp. Us5760266a method for the cyclotrimerization of alkynes in. Method for the cyclotrimerization of alkynes in aqueous. Intramolecular cyclotrimerization of triynes catalyzed by nheterocyclic carbene. In organic chemistry, an alkyne is an unsaturated hydrocarbon containing at least one carboncarbon triple bond. Simple alkynes are named much like alkenes, except the ending is changed fromane toyne. Catalyzed hydrophosphination and cyclotrimerization of alkynes. Pdf room temperature niii catalyzed hydrophosphination and. Cyclotrimerization an overview sciencedirect topics. A number of new alkynes derivatives are now available through alfa aesar. Elwahya, achemistry department, faculty of science, cairo university, giza, egypt b chemistry department, faculty of applied science, umm alqura university, makkah almukkarramah, saudi arabia. Cyclotrimerization of alkynes catalyzed by transition metal complexes is a straightforward synthetic method for constructing a benzene skeleton in organic. Photoorganoiron catalysis for the cyclotrimerization of alkynes.
Room temperature niii catalyzed hydrophosphination and. These data are consistent with the accepted dissociative mechanisms of cobaltcatalyzed alkyne cyclotrimerization. Cyclotrimerization of alkynes using a multicatalytic system. Jan 28, 2005 a highly regioselective intermolecular cyclotrimerization of terminal alkynes has been developed based on the use of the cationic rhodiumidtbm. For example, phenylacetylene affords both 1,3,5 and 1,2,4c 6 r 3 h 3. Regioselective cyclotrimerization of terminal alkynes using a.
Note that if a terminal alkyne is produced, the strong base will deprotonate the alkyne to form an alkynide anion. S1 electronic supplementary information cyclotrimerization of alkynes catalyzed by a selfsupported cyclic trinuclear nickel0 complex with. Request pdf photoorganoiron catalysis for the cyclotrimerization of alkynes successful combinations of visible light photocatalysis with transition metal catalysis have recently enabled the. Methods of preparation of alkynes by dehydrohalogenation. Br 3 co 8 with internal and terminal alkynes afford alkyne adducts, the reaction of net 4nb 2. Photoorganoiron catalysis for the cyclotrimerization of. Translated from izvestiya akademii nauk sssr, seriya khimicheskaya, no. At this point the remaining acyl hydride turns over. Metalfree synthesis of 1,3,5trisubstituted benzenes by. Transitionmetalcatalyzed cyclotrimerization of alkynes is a useful method for the construction of substituted benzenes. Diketiminates have been proven to be incredibly effective ligands for catalysis using a range of metal centers. The preference for electron poor alkynes is commonly observed in nicatalyzed cyclotrimerization of terminal alkynes. Compounds 24 all show a structure with each vanadium atom being. The loss of a hydrogen atom and a halogen atom from adjacent alkane carbon atoms leads to the formation of an alkene.
Molecular and structural formulas the alkynes comprise a series of carbon. Some of the important methods of preparation of alkynes are. Being a cycloaddition reaction, it has high atom economy. Internal alkynes such as 3hexyne and 4octyne were converted into hexaethyl and hexapropylbenzenes in quantitative yields. Trimerization of unsymmetrical alkynes gives two isomeric benzenes.
Cobaltcatalyzed cyclotrimerization of alkynes in aqueous. Cyclotrimerization of monosubstituted alkynes in the presence. Enhanced catalytic activity of nickel complexes of an. In the presence of excess alkyne, compounds 1, 3, and 4 turned out to be active species for the catalytic carbon.
Bpi benzophenone imine has previously been shown to act as an active and selective alkyne cyclotrimerization catalyst. Methods of preparation of alkynes by dehydrohalogenation of. Reaction in which the elements of water h and oh are. Ustynyuk for providing molybdenum and tungsten carbonyl derivatives. This method can be applied to a variety of terminal alkynes to provide 1,2,4.
Alkynes are highly reactive and the triple bond can exert remarkable effects on the rest of the molecule through. The query cyclotrimerization of alkynes resulted in 59 hits. Us6225500b1 method for the cyclotrimerization of alkynes. Catalyzed alkyne trimerization for macrocyclizations with arkivoc. The preparations of alkynes are very similar to those of the alkenes. Procedures have been developed for the cyclotrimerization of nitriles which use. Further reaction of the products with alkynes leads to alkyne trimerization compounds, dienynes, and alkyne cyclotrimerization compounds. This group of compounds is a homologous series with the general molecular formula of c n h 2 n2, where n equals any integer greater than one. Many variations have been developed including cyclization of mixtures of alkynes and. Us6225500b1 method for the cyclotrimerization of alkynes in. Alkynes are similar to alkenes in both physical and chemical properties.
Nickelcatalyzed alkyne cyclotrimerization assisted by a. By analyzing the position of the query term as being either in the title or in the text of the entries in the resulting hitlist, and the position of the selected document in the table of contents, we found it easy to assess the usefulness of the hits. Further reaction of the products with alkynes leads to alkyne trimerization. The substitution pattern about the product arene is determined in two steps. In some cases, nitriles can be cocyclized with alkynes to give heteroatomsubstituted rings. Compound 2 catalyzes the cyclotrimerization of a variety of internal.
Rutheniumcatalyzed intermolecular 2 2 2 alkyne cyclotrimerization in aqueous media under microwave irradiation victorio cadierno, javier francos, sergio e. This method was once an important industrial process for the manufacture of acetylene. Calcium carbide is prepared by heating quicklime with coke. Terminal alkynes can function as weak acids if you react them with a very strong base. Although various transition metals catalyze alkyne cyclotrimerization, it has been difficult to carry out that intermolecular reaction in a highly regioselective manner.
Many have already been extensively cited in the scientific literature. A number of transition metal alkyne complexes are intermediates in the cyclotrimerization of alkynes to substituted benzenes. Cyclotrimerization of alkynes catalyzed by a selfsupported. Cyclotrimerization of internal and terminal alkynes was performed using a new triple catalytic system, pdiichlorohydroquinonenpmov, under atmospheric oxygen. Cyclotrimerization of alkynes using a multicatalytic. Metallacyclopentadienes, generated from the reductive coupling of two alkyne molecules, constitute viable intermediates in metalcatalyzed alkyne cyclotrimerization catalysis. The international union of pure and applied chemistry iupac names for alkynes parallel those of alkenes, except that the family ending is yne rather than ene. The reaction of b with another alkyne molecule was studied in order to elucidate likely reaction intermediates and transition states. Pdf cyclotrimerization of arylalkynes on au111 pascal. The main preparative reactions involve the elimination of groups or ions from molecules, resulting in the formation of. A highly regioselective intermolecular cyclotrimerization of terminal alkynes has been developed based on the use of the cationic rhodiumidtbm. Recent advances in the transitionmetalcatalyzed regioselective.
Metalfree synthesis of 1,3,5trisubstituted benzenes by the cyclotrimerization of enaminones or alkynes in water jieping wan,a,b yunfang lina kaikai hua and yunyun liua,b acollege of chemistry and chemical engineering, jiangxi normal university, nanchang 330022, p. Mechanistic understanding of alkyne cyclotrimerization on. Complex 2 is able to catalyze the cyclotrimerization of alkynes to form substituted benzenes in good yield and regioselectivity for the 1,3,5isomers, which is found to vary with the nature of the alkyne employed. Cyclotrimerization of alkynes catalyzed by a selfsupported cyclic trinuclear nickel0 complex with.
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