1,3-Butadiene, transition-metal-catalyzed

In addition to the applications reported in detail above, a number of other transition metal-catalyzed reactions in ionic liquids have been carried out with some success in recent years, illustrating the broad versatility of the methodology. Butadiene telomerization [34], olefin metathesis [110], carbonylation [111], allylic alkylation [112] and substitution [113], and Trost-Tsuji-coupling [114] are other examples of high value for synthetic chemists. 

The d-lactone (Scheme 38.11) can be efficiently obtained by the telomerization of butadiene and C02. Its biphasic hydrogenation with an in-situ-prepared Rh/ mtppts catalyst yields 2-ethylidene-6-heptenoic acid (and its isomers) [136]. Note, that the catalyst is selective for the hydrogenolysis of the lactone in the presence of two olefmic double bonds this is probably due to the relatively large [P] [Rh] ratio (10 1) which is known to inhibit C = C hydrogenations with [RhCl(wtppms)3]. The mixture of heptenoic acids can further be hydrogenated on Pd/C and Mo/Rh catalysts to 2-ethylheptanol which finds several applications in lubricants, solvents, and plasticizers. This is one of the rare examples of using C02 as a Cl building block in a transition metal-catalyzed synthetic process. 

A typical (industrially applied) example for the synthesis of monoalkylglyceryl ethers [39, 40] consists of the transition metal-catalyzed conversion of glycerol and butadiene (telomerization) to yield glyceryl unsaturated octyl and dioctyl ethers (Scheme 11.5). 

Whereas the transition metal catalyzed cyclotrimerization and cyclotetramerization of alkynes leading to benzene or cyclooctatetraene and their derivatives is a rather common reaction, there exist only a few examples of cooligomerizations between alkynes and alkenes or 1,3-butadienes leading to 1,3- or 1,4-cyclohexadiene derivatives20S). It is therefore surprising that the [3+2]-cycloaddition between methylenecyclopropanes and alkynes, catalyzed by triarylphosphite modified Ni(0) compound, is a rather convenient method to synthesize 4-methylenecyclopentenes 206). A wide range of methylenecyclopropanes and alkynes, in the latter case mainly 1,2-disubstituted ones, can be used for these reactions (Eqs. 98-100, see p. 127-128). 

This behaviour correponds to the observation that other unsaturated hydrocarbons, e.g. alkynes, allenes or 1,3-butadienes, which readily undergo transition metal catalyzed cyclooligomerizations, do also incorporate CX multiple bonds in such cycloadditions only with difficulty in most cases 207 208). Besides the well known cobalt-catalyzed pyridin synthesis from alkynes and nitriles98 cocyclooligomerizations have been achieved with alkynes on one side and isocyanates 209), carbodiimides210) and carbondioxide 211) on the other side as well as with 1,3-butadienes and aldehydes 212), carbondioxide213 and 2-aza- or 2,3-diaza- 1,3-butadiene214. ... 

The addition of HCN to C=C double bonds can be effected in low yields to produce Markovnikov addition products. However, through the use of transition metal catalysts, the selective anti-Markovnikov addition of HCN to alkenes can take place. The most prominent example of the use of aqueous media for transition metal-catalyzed alkene hydrocyanation chemistry is the three-step synthesis of adi-ponitrile from butadiene and HCN (Eqs. 5-7). First discovered by Drinkard at DuPont [14], this nickel-catalyzed chemistry can use a wide variety of phosphorus ligands [15] and is practiced commercially in nonaqueous media by both DuPont and Butachimie, A DuPont/Rhone-Poulenc joint venture. Since the initial reports of Drinkard, first Kuntz [16] and, more recently, Huser and Perron [17, 18] from Rhone-Poulenc have explored the use of water-soluble ligands for this process to facilitate catalyst recovery and recycle from these high-boiling organic products. 

Several reviews compile general aspects of the applications of transition metal catalyzed hydrocyanation of alkenes and alkynes1-6. This method is synthetically interesting since, starting from nonactivated alkenes. access is achieved not only to nitriles, but also to carboxylic acid derivatives, amines and isocyanates. Of industrial importance is the double addition of hydrogen cyanide to butadienes yielding adipodinitrile7,8. 

Chiral aminophosphane-phosphinites (AMPP), prepared by the reaction of chloro(diphenyl)-phosphane with optically active amino alcohols, such as ephedrines, prolinol and A -methyl-phenylglycinol, are used as ligands in transition metal catalyzed cyclodimerization of butadiene to 4-vinylcyclohexene62,10 . With a nickel(0)LJ catalyst (L = Proliphos), (—)-4-vinylcyclo-hexene with 15% ee was obtained in 50% yield6. ... 

This behaviour correponds to the observation that other unsaturated hydrocarbons, e.g. alkynes, allenes or 1,3-butadienes, which readily undergo transition metal catalyzed cyclooligomerizations, do also incorporate CX multiple bonds in such cycloadditions only with difficulty in most cases Besides the well known cobalt-... 

Abstract The transition-metal-catalyzed cyclooligomerization of 1,3-dienes and the cooligomerization of 1,3-dienes and alkenes, that involve the stereoselective formation of carbon-carbon bonds, are of great interest from both a scientific as well as an industrial point of view. In this account a theoretical well founded, comprehensive mechanistic view of the [Ni ]-catalyzed co-oUgomerization of 1,3-butadiene and ethylene is presented. The... 

Transition metal catalyzed hydrogenation in ionic liquids has also been applied to the hydrogenation of polymers. First studies were presented by Dupont s group which investigated the hydrogenation of acrylonitrile-butadiene copolymers [102]. These early studies were later expanded by Rosso and coworkers studying the rhodium catalyzed hydrogenation of polybutadiene (PBD), nitrile-butadiene rubber (NBR) and styrene-butadiene rubber (SBR) in a [BMIM][BF4]/toluene and a... 

Efficient transition metal catalyzed hydration of 1,3-butadiene could replace the use of sulfuric acid in the production of the important industrial chemical 2-butanone (methyl ethyl ketone), thereby eliminating environmental and corrosion problems. In this reaction, a mixture of [Ru(acac)3] and 2,2 -bipyridine or 1,10-phenantroline together with an excess of a Bronsted acid gave promising results (223) (Scheme 42). 

The ability of the diboronyl reagents to undergo transition-metal catalyzed additions onto unsaturations has been put to use in the preparation of allylboronates. For example, Miyaura and co-workers described the formation of bis(allylboronates) like 25 by diboration of symmetrical dienes with reagent 24 under platinum catalysis (Equation 13) [46]. Norman and co-workers applied this process to the coupling between chiral diboronyl reagents and 1-substituted-l,3-butadienes [47]. Although high yields and clean conversions were observed, the diastereoselectivity in the formation of chiral 1-substituted allylboronates was very low. 

Pd-cataly2ed reactions of butadiene are different from those catalyzed by other transition metal complexes. Unlike Ni(0) catalysts, neither the well known cyclodimerization nor cyclotrimerization to form COD or CDT[1,2] takes place with Pd(0) catalysts. Pd(0) complexes catalyze two important reactions of conjugated dienes[3,4]. The first type is linear dimerization. The most characteristic and useful reaction of butadiene catalyzed by Pd(0) is dimerization with incorporation of nucleophiles. The bis-rr-allylpalladium complex 3 is believed to be an intermediate of 1,3,7-octatriene (7j and telomers 5 and 6[5,6]. The complex 3 is the resonance form of 2,5-divinylpalladacyclopentane (1) and pallada-3,7-cyclononadiene (2) formed by the oxidative cyclization of butadiene. The second reaction characteristic of Pd is the co-cyclization of butadiene with C = 0 bonds of aldehydes[7-9] and CO jlO] and C = N bonds of Schiff bases[ll] and isocyanate[12] to form the six-membered heterocyclic compounds 9 with two vinyl groups. The cyclization is explained by the insertion of these unsaturated bonds into the complex 1 to generate 8 and its reductive elimination to give 9. 

Coupling of butadiene with CO2 under electrochemically reducing conditions produces decadienedioic acid, and pentenoic acid, as weU as hexenedioic acid (192). A review article on diene telomerization reactions catalyzed by transition metal catalysts has been pubUshed (193). 

The 7r-back donation stabilizes the alkene-metal 7c-bonding and therefore this is the reason why alkene complexes of the low-valent early transition metals so far isolated did not catalyze any polymerization. Some of them catalyze the oligomerization of olefins via metallocyclic mechanism [25,30,37-39]. For example, a zirconium-alkyl complex, CpZrn(CH2CH3)(7/4-butadiene)(dmpe) (dmpe = l,2-bis(dimethylphosphino)ethane) (24), catalyzed the selective dimerization of ethylene to 1-butene (Scheme I) [37, 38]. 

The catalytic cyclo-oligomerization of 1,3-butadiene mediated by transition-metal complexes is one of the key reactions in homogeneous catalysis.1 Several transition metal complexes and Ziegler-Natta catalyst systems have been established that actively catalyze the stereoselective cyclooligomerization of 1,3-dienes.2 Nickel complexes, in particular, have been demonstrated to be the most versatile catalysts.3... 

Reactions of conjugated 1,3-dienes, mainly butadiene and isoprene, catalyzed by transition metal complexes to form a number of linear and cyclic oligomers and telomers, are one of the most fascinating fields of research in the last 20 years. Extensive studies from academic and in-... 

Polybutadiene and polyisoprene are produced and used mainly as synthetic rubber on an industrial scale by using transition metal catalysts, especially titanium- and nickel-based ones. By contrast, only minor attention has been paid to the palladium-catalyzed polymerization of butadiene. A mixture of 1,2-polybutadiene and trans- and c/s-l, 4-polybutadiene was obtained by using PdCl2 as a catalyst (7, 2). 

Among transition metal complexes used as catalysts for reactions of the above-mentioned types b and c, the most versatile are nickel complexes. The characteristic reactions of butadiene catalyzed by nickel complexes are cyclizations. Formations of 1,5-cyclooctadiene (COD) (1) and 1,5,9-cyclododecatriene (CDT) (2) are typical reactions (2-9). In addition, other cyclic compounds (3-6) shown below are formed by nickel catalysts. Considerable selectivity to form one of these cyclic oligomers as a main product by modification of the catalytic species with different phosphine or phosphite as ligands has been observed (3, 4). 

After that, studies on the palladium-catalyzed reactions of conjugated dienes attracted little attention. They have only been reexamined since the late 1960 s. The scope of the reaction of butadiene catalyzed by palladium complexes has gradually been established. The catalysis by palladium is different from those of other transition metals. Although palladium is located below nickel in the periodic table, the catalytic... 

Other transition metal complexes also catalyzed the dimerization of simple butadiene type substrates. For related examples see ... 

It is well known that soluble copper or other transition metals will catalyze Aldol condensation reactions(29). The optimum copper(ll)/palladium(ll) molar ratio is 2.3. Normally, about 1500 ppm palladium is used in the butadiene oxycarbonylation reaction. Under typical oxycarbonylation process conditions, around. 5 mole % l, l-dimethoxycyclohexane is lost to heavies per pass. 

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