Diene reactions with carbon monoxide

Formation of the complexes 47c, 47e, and 47t and their smooth reaction with carbon monoxide sheds some light on the mechanism of [6 + 4] cycloaddition in the coordination sphere of chromium. Obviously, the photoreaction proceeds stepwise. First, the diene is coordinated to an activated complex (45) and forms tricarbonyl-t/4-8,8-dimethylheptafulvene-t/2-... 

The transfer of halide from 7r-allylnickel halide to aluminum to give a haloaluminum anion results in a strong decrease in the electron density and formation of free coordination positions on nickel. The presence and number of free coordination positions can be demonstrated by reaction with carbon monoxide. The catalytically active complex, XIII, reacts at —40°C. with 2 moles of carbon monoxide to give the inactive XIV which can be isolated. In XIII, there are accordingly two free coordination positions. During catalysis, these positions are presumably occupied by olefins in the form of 7r-complexes. A stable olefin 7r-complex, 7r-allylnickel (7T-cycloocta-l,5-diene) aluminum tetrabromide, XV, can actually be isolated by adding cycloocta-l,5-diene to a solution of the active complex, XIII. 

Novel types of polyamines and cationic polyelectrolytes form from polymers of conjugated dienes in reactions with carbon monoxide, amines, and water at 150 °C and 1000-1500 psi pressure. The reaction can be illustrated as follows ... 

For a long time experiments failed to produce normal carbonylation products starting from dienes. Under the usual conditions the conjugated dienes underwent a Diels-Alder reaction with subsequent hydrocarboxylation of the prior formed isolated alicyclic dienes. Thus, e. g. butadiene first reacted to give vinylcyclohexene which then yielded a mixture of dicarboxylic adds [493]. In other cases cyclic ketones were obtained from dienes and carbon monoxide (see section on ring closure reaction with carbon monoxide). 

Tris(allyl)rhodium(in) was reported to react with the hydroxyl-terminated surfaces of silica, titania and alumina to form a surface bis(allyl)rhodium(III) fragment, which on reaction with carbon monoxide afforded hexa-1,5-diene in quantitative fashion by reductive coupling of two allyl ligands. 

The polymers prepared from thexylborane and diene monomers were reacted with carbon monoxide at 120°C, followed by treatment with NaOH and H202 to produce a polyalcohol (scheme 5).13 This conversion includes migration of the polymer chain and thexyl group from the boron atom to carbon, as shown in scheme 5. When this reaction was carried out under milder condition, poly(ketone) segments were included in the polymer backbone due to an incomplete migration of the thexyl group. 

The acid-catalyzed hydrocarboxylation of olefins (the Koch reaction) can be performed in a number of ways.565 In one method, the olefin is treated with carbon monoxide and water at 100 to 350°C and 500 to 1000 atm pressure with a mineral-acid catalyst. However, the reaction can also be performed under milder conditions. If the olefin is first treated with CO and catalyst and then water added, the reaction can be accomplished at 0 to 50°C and 1 to 100 atm. If formic acid is used as the source of both the CO and the water, the reaction can be carried out at room temperature and atmospheric pressure.566 The formic acid procedure is called the Koch-Haaf reaction (the Koch-Haaf reaction can also be applied to alcohols, see 0-103). Nearly all olefins can be hydrocarboxylated by one or more of these procedures. However, conjugated dienes are polymerized instead. 

W-(2-Aminoethyl)-l,2-diaminoethane (dien) yields complexes [PdX(dien)]X (X = Cl or I) 204,20s a range of solvated complexes may be obtained by reaction of [Pdl(dien)] with AgC104 in the appropriate solvent. As for the platinum analogue, the aqua complex [Pd(dien)(H20)](C104)2 reacts with tetraphenylborate to yield [PdPh(dien)](BPh4). Reaction of the hydroxo complex with carbon monoxide yields C02 and palladium metal is deposited.206... 

RhCl(PPh3)3] (23) and [RhCl(CO)(PPh3)2] (71) catalyze the formation of enol silyl ethers and derivatives according to equation (86). Both the (E) and (Z) isomers of the product are obtained.4353 The dinuclear complex [Rh2Cl2(CO)4] (96) catalyzes the reaction of phenylacetylene with carbon monoxide to give 3,6-diphenyl-l-oxabicyclo-[3.3.0]-octa-3,6-diene-2,4-dione (97) (equation 87).435b... 

It has been recently reported that the reactions of 1,4-dilithio-l,3 dienes with carbon monoxide provides a useful tandem methodology for the synthesis of cyclopentenones14. The reaction constitutes an unprecedented pattern of highly selective efficient carbonylation, since in 1 h at — 78 °C it affords, after hydrolysis, fraws-3-cyclopenten-l-one in an excellent isolated yield and with perfect trans selectivity. 

Isomeric (s-cis- and (i-fra/w-V-conjugated diene)zirconocene and -haf-nocene complexes exhibit pronounced differences in their characteristic structural data as well as their spectroscopic features. These differences exceed by far the consequences expected to arise simply from the presence of conformational isomers of the 1,3-diene unit. While (f-rra/u-butadiene)-zirconocene (3a) shows a behavior similar to a transition metal olefin TT-complex, the (.r-cu-diene)ZrCp2 isomer 5a exhibits a pronounced alkylmetal character (23, 45). Typical features are best represented by a tr, 7T-type structure for 5 (55). However, the distinctly different bonding situation of the butadiene Tr-system/bent-metallocene linkage is not only reflected in differences in physical data between the dienemetallocene isomers 3 and 5, but also gives rise to markedly different chemical behavior. Three examples of this are discussed in this section the reactions of the 3/5 isomeric mbcture with carbon monoxide, ethylene, and organic carbonyl compounds. 

By the nature of its molecular mechanism, the carbonyl-insertion reaction represents a typical reaction mode of o alkyltransition metal complexes. Formation of the new C—C cr-bond takes place during a 1,2-alkyl-migration step, transforming an alkylmetal carbonyl moiety [cts-M(CO)R] into an acylmetal unit (M—COR) (89). In general, (s-cir-diene)-zirconocene complexes 5 appear to exhibit a substantial alkylmetal character (90). Therefore, it is not too surprising that some members of this class of compounds [in contrast to most other dienetransition metal complexes (97)] react with carbon monoxide with C—C bond formation (45). However, as demonstrated by X-ray structural data for 5 (Tables V... 

Reaction of (5-ci,s-Conjugated diene)zirconocene Complexes with Carbon Monoxide—Relative Carbonylation Rates and Product Yields... 

The oligomerization and cooligomerization of conjugated dienes are representative reactions that proceed via transition-metal Jt-allyl intermediates. When (CsMesjRuCljt/ -butadiene) in dichloromethane was treated with an acetone solution of an equimolar amount of silver trifluoromethanesulfonate (AgOTf) in the presence of excess butadiene at ambient temperature, after which the mixture was allowed to react with carbon monoxide (1 atm), a cationic 1,5-cyclooctadiene carbonyl complex, [(C5Me5)Ru(CO)( -l,5-C8Hi2)]OTf, was isolated in 95% yield (Eq. 

Various reactions have been described in which the transition metal has become part of a cyclic system ( metallacycles ) on reaction with the double bond of methylenecyclopropane. (2,2 -Bipyridine)(cycloocta-l,5-diene)nickel reacted with an excess of methylenecyclopropane to give 8-(2,2 -bipyridyl)-8-nickeladispiro[2.1.2.2.]nonane (4) in excellent yield.When this nickel compound was treated with carbon monoxide, dispiro[2.1.2.2.]nonan-8-one (5) was obtained in 50% yield. ... 

Besides [m + n] cycloadditions and [m 4- m + m +. ..] cyclo- and cocyclooligomerizations of alkenes, dienes or alkynes (see Sections 1.5.8.3.5, and 1.5.8.3.6.), transition metal complexes can also catalyze the cycloaddition of more than two different components. Most important is carbonylative ring synthesis with carbon monoxide as the C, unit. Several methods of this type use transition metals stoichiometrically, others catalytically. For some of the stoichiometric methods, developments towards catalytic versions are under way (e g., the Pauson-Khand reaction, see below). 

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