Palladium-catalyzed sequential formation of C-C bonds: efficient assembly of 2-substituted and 2,3-disubstituted quinolines

A series of substituted quinolines was prepared from arylamines, aldehydes, and terminal olefins (see scheme). The palladium-catalyzed sequential formation of C-C bonds proceeds smoothly with both electron-deficient and electron-rich olefins. When acrylic acid is used as terminal olefin, decarboxylation occurs to provide 2-substituted quinolines.     

Transition metal-catalyzed cyclopropanation of alkenes in fluorinated alcohols

The system hexafluoroisopropanol/ethyl diazoacetate/Cu(OTf)₂ is efficient for the cyclopropanation reaction. The process is experimentally simple, and efficient with various olefins in particular terminal, disubstituted double bonds.     

Catalytic scaffolding ligands: an efficient strategy for directing reactions

The design and application of a scaffolding ligand that promotes branch and diastereoselective hydroformylation of terminal olefins as well as the regio- and diastereoselective hydroformylation of disubstituted olefins is reported. It is shown that the ligand covalently and reversibly bonds to the substrate, allowing for directed hydroformylation. As the substrate ligand interaction is dynamic, hydroformylations are catalytic in ligand and do not require any additional synthetic steps to add or remove the directing group. Using a catalytic quantity of a scaffolding ligand (20-25 mol %), excellent regioselectivity for disubstituted olefins (up to 98:2) and high branch selectivity (up to 88:12) for terminal olefins were obtained.     

Self-assembly of naphthalene diimides into cylindrical microstructures

We have designed two rod-shaped compounds each incorporating a naphthalene diimide core and two terminal carboxylic acids. Both molecules aggregate in aqueous solution and spontaneously organize into cylindrical microstructures on the surface of solid substrates. Presumably, hydrogen bonds between the carboxylic acid termini and hydrophobic contacts between the naphthalene diimide cores are mainly responsible for the formation of these supramolecular arrays. Indeed, extended stacks of molecules self-assemble with close contacts between their aromatic cores in single crystals grown from polar solvents.     

Bis(Cyclic Alkyl Amino Carbene) Ruthenium Complexes: A Versatile,Highly Efficient Tool for Olefin Metathesis

The state‐of‐the‐art in olefin metathesis is application of N‐heterocyclic carbene (NHC)‐containing ruthenium alkylidenes for the formation of internal C=C bonds and of cyclic alkyl amino carbene (CAAC)‐containing ruthenium benzylidenes in the production of terminal olefins. A straightforward synthesis of bis(CAAC)Ru indenylidene complexes, which are highly effective in the formation of both terminal and internal C=C bonds at loadings as low as 1 ppm, is now reported.     

Bis(Cyclic Alkyl Amino Carbene) Ruthenium Complexes: A Versatile,Highly Efficient Tool for Olefin Metathesis

The state‐of‐the‐art in olefin metathesis is application of N‐heterocyclic carbene (NHC)‐containing ruthenium alkylidenes for the formation of internal C=C bonds and of cyclic alkyl amino carbene (CAAC)‐containing ruthenium benzylidenes in the production of terminal olefins. A straightforward synthesis of bis(CAAC)Ru indenylidene complexes, which are highly effective in the formation of both terminal and internal C=C bonds at loadings as low as 1 ppm, is now reported.     

A novel [2 + 2 + 1]/[2 + 1] tandem cycloaddition reaction of Fischer alkynyl carbenes with strained bicyclic olefins

The reaction of strained bicyclic olefins with alkynyl carbenes and terminal olefins involves the creation of five new sigma C-C bonds with the concomitant formation of two new rings, thus creating a complex and densely functionalized structure in a single operation.     

User‐Friendly Platinum Catalysts for the Highly Stereoselective Hydrosilylation of Alkynes and Alkenes

With a view to addressing the shortcomings of traditional catalysts, a new generation of outstanding N‐ heterocyclic carbene platinum(0) complexes for the hydrosilylation of unsaturated carbon–carbon bonds is reported. Their discovery and application to the stereoselective addition of various silanes to silylated alkynes, terminal acetylenes, and olefins is presented. Insights into the catalytic cycle and the origin of the stereoselectivity are also discussed.     

Selective dimerization,oligomerization, homopolymerization and copolymerization of olefins with complex organometallic catalysts

Review embarrasses the problems of low molecular weight olefins (ethylene and propylene) selective oligomerization to butene-1, hexene-1, octene-1, 4-methylpentene-1; selective polymerization of olefins to obtain polymers with a given molecular mass, molecular mass distribution, branching (for the polyethylene), chain structure [atactic, iso-, syndio-, gemiisotactic, stereoblock type and containing terminal vinyl and vinylidene bonds (for polypropylene)]; “live” homo-and copolymerization of olefins, and alternating copolymerization of olefins in the presence of complex organometallic catalysts.     

Selectivity Aspects in Cross Metathesis Reactions

When certain catalysts that display a low apparent metathesis activity on terminal olefins are employed on mixtures of terminal and internal olefins, they lead to a selective formation of cross metathesis products. Critical experimentation using deuterated 1-pentene reveals that terminal olefins prefer to scramble “head-to-tail”. A study of the macrocyclics distribution produced at various conversions during 1,5-cycloocta-diene polymerization suggests that these are being formed exclusively via an intramolecular transalkylidenation. The significance of the two sets of results is discussed in terms of two basic mechanistic schemes.     

Aromatic-amide-derived olefins as a springboard: isomerization-initiated palladium-catalyzed hydrogenation of olefins and reductive decarbonylation of acyl chlorides with hydrosilane

A highly efficient catalytic protocol for the isomerization of substituted amide-derived olefins is presented that successfully uses a hydride palladium catalyst system generated from [PdCl(2)(PPh(3))(2)] and HSi(OEt)(3). The Z to E isomerization was carried out smoothly and resulted in geometrically pure substituted olefins. Apart from the cis-trans isomerization of double bonds, the selective reduction of terminal olefins and activated alkenes was performed with excellent functional group tolerance in the presence of an amide-derived olefin ligand, and the products were obtained in high isolated yields (up to >99?%). Furthermore, the palladium/hydrosilane system was able to promote the reductive decarbonylation of benzoyl chloride when a (Z)-olefin with an aromatic amide moiety was used as a ligand.     

Steel-promoted oxidation of olefins in supercritical carbon dioxide using dioxygen in the presence of aldehydes

Oxidation of olefins occurs effectively in supercritical carbon dioxide as the reaction medium with dioxygen as the primary oxidant and aldehydes as sacrificial co-oxidants. No catalyst is required, but the reaction is promoted by the stainless steel of the reactor walls. Depending on the substrate, vinylic oxidation or epoxidation can be the prevailing pathway. Epoxidation is particularly effective for substrates with internal double bonds and for long-chain terminal olefins.     

Efficient epoxidation reaction of terminal olefins with hydrogen peroxide catalyzed by an iron (II) complex

A highly active iron (II) complex that catalyzed epoxidation of terminal olefins with hydrogen peroxide was described. The catalytic system displayed excellent catalytic ability for the selective oxidation of terminal olefins to epoxides with high selectivity (up to 97.8%) in CH₃CN at 25?°C. The catalytic activity of three similarly structural iron (II) complexes was comparatively studied. The effect of various auxiliary ligands on epoxidation was investigated in detail.     

Aerobic reduction of olefins by in situ generation of diimide with synthetic flavin catalysts

A versatile reducing agent, diimide, can be generated efficiently by the aerobic oxidation of hydrazine with neutral and cationic synthetic flavin catalysts 1 and 2. This technique provides a convenient and safe method for the aerobic reduction of olefins, which proceeds with 1 equiv of hydrazine under an atmosphere of O(2) or air. The synthetic advantage over the conventional gas-based method has been illustrated through high hydrazine efficiency, easy and safe handling, and characteristic chemoselectivity. Vitamin B(2) derivative 6 acts as a highly practical, robust catalyst for this purpose because of its high availability and recyclability. Association complexes of 1b with dendritic 2,5-bis(acylamino)pyridine 15 exhibit unprecedented catalytic activities, with the reduction of aromatic and hydroxy olefins proceeding significantly faster when a higher-generation dendrimer is used as a host pair for the association catalysts. Contrasting retardation is observed upon similar treatment of non-aromatic or non-hydroxy olefins with the dendrimer catalysts. Control experiments and kinetic studies revealed that these catalytic reactions include two independent, anaerobic and aerobic, processes for the generation of diimide from hydrazine. Positive and negative dendrimer effects on the catalytic reactions have been ascribed to the specific inclusion of hydrazine and olefinic substrates into the enzyme-like reaction cavities of the association complex catalysts.     

Les spectres de masse dans l'analyse 9e communication [1] Le réarrangement de doubles liaisons sous bombardement d'électrons

Using suitably deuteriated olefins, it is shown that electron bombardment of compounds having double bonds exocyclic to six-membered rings apparently causes migration of the double bond into the ring. Isopropenylcyclohexanes, on the other hand, appear to behave as if the radical were fixed on the terminal carbon, while the charge migrates by 1,2 hydrogen transfers.     

Catalytic intermolecular C-alkylation of 1,2-diketones with simple olefins: a recyclable directing group strategy

We describe the first example of Rh-catalyzed intermolecular C-alkylation of cyclic 1,2-diketones using simple terminal olefins as alkylating agents. Aminopyridine is employed as a recyclable directing group. First, it reacts with ketones to give enamines and delivers Rh to activate the vinyl C-H bonds in the same pot; second, it can be cleaved off and recovered via hydrolysis. A broad range of olefins can be utilized as substrates, including aliphatic, aromatic olefins and vinyl esters. The efficiency of this method is also demonstrated in the synthesis of a natural flavoring compound, 3-ethyl-5-methyl-1,2-cyclopentadione (one-pot 53% yield vs a previous four-step route 16% yield from the same starting material). This work is expected to serve as a seminal study toward catalytic ketone α-alkylation with unactivated olefins.     

Intermolecular,Branch‐Selective,and Redox‐Neutral Cp*IrIII‐Catalyzed Allylic C−H Amidation

Herein, we report the redox‐neutral, intermolecular, and highly branch‐selective amidation of allylic C?H bonds enabled by Cp*Ir^III catalysis. A variety of readily available carboxylic acids were converted into the corresponding dioxazolones and efficiently coupled with terminal and internal olefins in high yields and selectivities. Mechanistic investigations support the formation of a nucleophilic Ir^III–allyl intermediate rather than the direct insertion of an Ir–nitrenoid species into the allylic C?H bond.     

Catalytic oxidative cleavage of terminal olefins by chromium(III) stearate

A new synthetic methodology for the preparation of carbonyl compounds from the oxidative cleavage of terminal olefins has been developed. With the use of TBHP in combination with chromium(III) stearate, selective oxidation of double bonds conjugated with aromatic ring or carbonyl group could be achieved at ambient temperature in moderate to excellent yield. The oxidative cleavage of electron rich -methylstyrene derivatives proceeded in good to excellent yield whereas lower yields were observed in -methylstyrene derivatives containing an electron withdrawing group. This developed oxidation reaction was believed to undergo via free radical process and high valent chromium oxo species.     

Aromatic‐Amide‐Derived Olefins as a Springboard: Isomerization‐Initiated Palladium‐Catalyzed Hydrogenation of Olefins and Reductive Decarbonylation of Acyl Chlorides with Hydrosilane

A highly efficient catalytic protocol for the isomerization of substituted amide‐derived olefins is presented that successfully uses a hydride palladium catalyst system generated from [PdCl₂(PPh₃)₂] and HSi(OEt)₃. The Z to E isomerization was carried out smoothly and resulted in geometrically pure substituted olefins. Apart from the cis–trans isomerization of double bonds, the selective reduction of terminal olefins and activated alkenes was performed with excellent functional group tolerance in the presence of an amide‐derived olefin ligand, and the products were obtained in high isolated yields (up to >99 %). Furthermore, the palladium/hydrosilane system was able to promote the reductive decarbonylation of benzoyl chloride when a (Z)‐olefin with an aromatic amide moiety was used as a ligand.     

Palladium-catalyzed double arylations of terminal olefins in acetic acid

A palladium-catalyzed Heck diarylation of terminal olefins under ligand-free conditions in acetic acid is described. This procedure allows double arylation of terminal olefins affording trisubstituted olefins in good to excellent yields. The methodology is applicable to the coupling of both electron-deficient and electron-rich aryl iodides leading to symmetrical and unsymmetrical β,β-diarylated alkenes.