Showing papers on "Norbornadiene published in 1968"

The preparation and reactions of hydridochlorotris(triphenylphosphine)ruthenium(II) including homogeneous catalytic hydrogenation of alk-1-enes

Abstract: The complex hydridochlorotris(triphenylphosphine)ruthenium(II) as a benzene solvate, RuClH(PPh3)3,C6H6, has been obtained by the interaction of the dichloride, RuCl2(PPh3)3, with molecular hydrogen at ambient temperature pressure in the presence of a base such as triethylamine; other preparative methods are described. The corresponding bromide, RuBrH(PPh3)3,C6H6, has been prepared. From the chloride by interaction with norbornadiene and 2,2′-bipyridyl, the complexes RuClH(C7H8)(PPh3)2 and [RuClH(bipyr)(PPh3)2]2 respectively have been obtained; the complex RuH2(CO)(PPh3)3 has also been prepared.The complex RuClH(PPh3)3 is the most active catalyst yet discovered for the homogeneous hydrogenation of alk-1-enes in benzene or toluene solution. The interaction is highly specific and rates for other types of alkene are slower by a factor of at least 2 × 103. The inherent difficulties of the system however preclude detailed kinetic study and it is shown that slow poisoning of the catalyst occurs under hydrogenation conditions.N.m.r. studies of the hydrido-complex and its deuteride have allowed hydrogen atom exchange studies to be made. Isomerisation of alkenes is studied. The slow exchange between molecular hydrogen and the α-proton of a phenyl group on the phosphine is demonstrated.

On Transition Metal-Catalyzed Reactions of Norbornadiene and the Concept of π Complex Multicenter Processes

Abstract: Publisher Summary This chapter focuses on bicyclo[22l]heptadiene-2,5 (norbornadiene), a new versatile substrate for catalytic studies The chapter describes its transition metal-catalyzed reactions and discusses the mechanism of these reactions and the function of transition metals in catalytic processes of this kind The chemistry of norbornadiene is characterized by strain and homoconjugation Hence, the olefin undergoes a series of addition reactions that are frequently accompanied by the formation of the nortricyclene system—the direction of electrophilic attack being usually exo Transition metal complexes, such as nickel carbonyl or bisacrylonitrile nickel have been found to greatly promote the reaction of acrylonitrile with norbornadiene Norbornadiene may be carbonylated essentially under the conditions of Reppe's acrylic ester synthesis

Transition metal–carbon bonds. Part XII. Allylic complexes of ruthenium(II)

Abstract: New allylic complexes of ruthenium(II) of the type [Ru(all)2(diolefin)](all = allyl or 2-methylallyl; diolefin cyclo-octa-1,5-diene or norbornadiene) are described. The allylic ligands in these complexes are asymmetrically bonded. The complexes react with allyl halides to give halogeno-bridged complexes of the type [Ru2X2(all)2(diolefin)2](X = Cl or Br). On treatment with triphenylphosphine cyclo-octa-1,5-diene is displaced from [Ru(2-methylallyl)2C8H12] giving [Ru(2-methylallyl)2(PPh3)2]. This in turn reacts with carbon monoxide to give [Ru(CO)3(PPh3)2] and 2,5-dimethylhexa-1,5-diene. Nuclear magnetic resonance and far-infrared data are given.

The catalytic dimerisation of dienes by nitrosylcarbonyl transition-metal compounds

Abstract: Butadiene and isoprene have been found to dimerise rapidly, under relatively mild conditions, by the catalytic action of dicarbonyldinitrosyliron and dicarbonyldinitrosyl(π-allyl)iron. Only norbornadiene is known to react in a similar manner, and the system appears unique in its indifference to additives. Sunlight, however, had a marked activating effect, decreasing the temperature required for high conversion of monomer from 100° to room temperature.

Addition of C-phenyl-N-methyl nitrone to norbornene and norbornadiene

Abstract: The reaction of C-phenyl-N-methyl nitrone with norbornene gave two 1:1 cycloadducts in a ratio of 9:1. Both adducts have been shown to possess an exo-cis isoxazolidine ring by nuclear magnetic resonance and to be diastereomeric at the benzylic carbon of the isoxazolidine ring by chemical degradation of both adducts to 3-exo-benzyl-2-exo-hydroxybicyclo [2•2•1] heptane. The reaction of the same nitrone with norbornadiene gave a 1:1 and a 2:1 adduct. The stereochemistry of the 1:1 adduct was shown to be the same as that of the major norbornene adduct which it gave on hydrogenation of the double bond. The structure of the 2:1 adduct was not investigated.

Photochemical cycloadditions of organic compounds

Abstract: — Oxetanes were synthesized by 1,2-photoaddition of benzophenone to several methyl-substituted furans. The photochemical conversion of oxobicyclic analogues of norbornadiene to the corresponding oxoquadricyclenes was studied, and finally the sensitized 1,2-photoaddition of citraconic anhydride to furan was accomplished. RESUMEN Se han sintetizado oxetanos por fotoadicion 1,2 de benzofenona a distintos metil furanos. Se ha estudiado la conversion fotoquimica de analogos oxobiciclicos del norbonadieno, y finalmente se ha logrado la fotoadicion 1,2 sensitivizada de anhidrido citraconico a furano.

Coordination compounds of norbornadiene with silver tetrafluoroborate

Abstract: Crystalline complexes of norbornadiene with silver tetrafluoroborate have been obtained both from anhydrous and aqueous solution While both solutions yield complexes of stoichiometry AgBF4•C7H8 an