Nonconjugated Dienes Research Articles

Selective initiation of nonconjugated dienes containing electron donor–electron acceptor systems. IV. Polymerization of vinyl ether–styrene monomers

AbstractThree isomeric nonconjugated dienes, o‐, m‐ and p‐(2‐vinyloxyethoxy)styrenes, were selectively polymerized by anionic or radical initiators through the styryl double bond while leaving the vinyl ether moiety intact. The anionic‐initiated polymeric products are of high molecular weight and narrow molecular weight distribution as characterized by membrane osmometry and gel‐permeation chromatography, respectively. These polymers were subsequently crosslinked by cationic initiators via the vinyl ether moiety on the polymer side chains. Acid‐catalyzed hydrolysis of the poly(2‐vinyloxyethoxy)styrenes yielded their respective hydroxy‐containing polymers, polyvinylphenoxyethanols. The latter were physically and spectroscopically identical to authentic samples prepared by radical polymerization of the corresponding vinylphenoxyethanols, which, in turn, were synthesized by hydrolysis of the (2‐vinyloxyethoxy)styrenes. The polyvinylphenoxyethanols were shown to undergo many chemical transformations, such as esterification with 3,5‐dinitrobenzoyl chloride, cyanoethylation, and urethane formation.

Study of hydrogenation of olefins catalyzed by polymer-bound palladium (II) complexes

A polymer-bound palladium (II) chloride complex has been prepared by the reaction of palladium chloride with a phosphinated polystyrene. Under mild conditions the polymer palladium complex catalyzes the hydrogenation of alkenes and alkynes, particularly the selective hydrogenation of conjugated dienes to monoenes. The catalytic activity for a variety of substrates decreases in the following order: conjugated dienes > nonconjugated dienes > terminal olefins > internal olefins. Oxygen-containing solvents remarkably promote the catalytic activity of the palladium complex. The rates of hydrogenation of cyclohexene, styrene, and 1,3-cyclooctadiene have been studied and the dependence on factors such as substrate concentration, catalyst concentration, pressure, and temperature has been determined. The data can be accommodated by rate expressions of the form: rate = k 1k 2[S][ H 2 ][A] (k −1 + k 1[S] + k 2[ H 2 ] for cyclohexene, and rate = k 2[H 2][ A] for styrene and 1,3-cyclooctadiene, where [ S] and [ A] are the olefin and catalyst concentrations, respectively, and [H 2] is the concentration of hydrogen in solution. A mechanism for hydrogenation is proposed on the basis of the kinetic studies. It is revealed that the reactivities of the polymer palladium complex catalyst and of an analogous catalyst system PdCl 2(PPh 3) 2SnCl 2 reflect the electronic state and the coordination number of the complexes.

Hydroboration. 48. Effect of structure on selective monohydroboration of representative nonconjugated dienes by 9-borabicyclo[3.3.1]nonane

Hydroboration. 48. Effect of structure on selective monohydroboration of representative nonconjugated dienes by 9-borabicyclo[3.3.1]nonane

ChemInform Abstract: SULFOXONIUM YLIDE CHEMISTRY. VIII. A NOVEL REARRANGEMENT OF DIMETHYLSULFOXONIUM YLIDES

AbstractDie Reduktion der Sulfoxoniumylide (I) mit Zn/Essigsäure verläuft über anionische Radikale zu den intermediären Cyclobutenen (II), deren Spaltproduk‐ te, die nicht konjugierten Diene (III), die konjugierten Isomeren (IV) und (V) liefern; die geometrischen Isomeren (IVb) und (Vb) werden in 5 1%iger Ausbeute im Verhältnis 40:60 erhalten.

Reaction of iodine with non-conjugated dienes; iodocyclization promoted by a remarkable gem-dialkyl effect

Reaction of iodine with non-conjugated dienes; iodocyclization promoted by a remarkable gem-dialkyl effect

A hydrogen-1 and carbon-13 nuclear magnetic resonance study of the bonding in some monosubstituted cyclopentadienyl complexes of rhodium(I) and the crystal and molecular structure of cyclo-octa-1,5-diene(η-methoxycarbonyl-cyclopentadienyl)rhodium(I)

The 1H and 13C n.m.r. spectra of a series of monosubstituted η-cyclopentadienylrhodium(I) complexes of the types [RhL2(C5H4X)] and [Rh(LL)(C5H4X)] are described (L = ethylene or CO; LL = a 1,3-, 1,4-. or 1,5-diene; X = Me, CMe3, CO2Me, CO2Et, CO2Pri, CHO, COCO2Et, or CN). For complexes where the substituent X is electron-withdrawing in nature and where the neutral ligand is ethylene or a non-conjugated diene the 1H spectra of the cyclopentadienyl ring protons show a novel temperature dependence (+40 to –60 °C) in CDCI3 involving a chemical-shift cross-over without line broadening of the H(2), H(5) and H(3), H(4) resonances. In contrast, the n.m.r. behaviour of the complexes of conjugated dienes is normal, The unusual spectra observed for the non-conjugated alkene complexes are attributed to unequal barriers for the rotation of the cyclopentadienyl ring leading, at the lower temperatures, to preferential population of a particular rotamer state. A single-crystal X-ray structure determination of [Rh(cyclo-octa-1,5-diene)(C5H4CO2Me)](1)suggests that the preferred rotamer in solution may be one in which the C5ring is bonded to the metal asan η-allyl via C(2), C(1), and C(5)[2.230(8), 2.256(6), 2.226(5)Å] with a weaker interaction via an alkene function localized between C(3) and C(4)[2.303(8), 2.294(7)Å]. A simple bonding model is proposed which relates the n.m.r. spectra of solutions to the structure of the solid and which accounts for the differences in behaviour between complexes of conjugated dienes on the one hand and those containing isolated double bonds on the other.

Sulfoxonium Ylide Chemistry. VIII. A Novel Rearrangement of Dimethylsulfoxonium Ylides

Abstract Reduction of dimethylsulfoxonium 3-ethoxycarbonyl-1-[1,2-bis(methoxycarbonyl)vinyl]-2-phenylallylide (1) and dimethylsulfoxonium 3-ethoxycarbonyl-1-[2-(ethoxycarbonyl)vinyl]-2-phenylallylide (5) with zinc in acetic acid gave (Z)- and (E)-3-methoxycarbonyl-4-ethoxycarbonyl-5-phenyl-3,5-hexadienoic acid methyl ester (6a and 6b), and (Z)- and (E)-4-ethoxycarbonyl-5-phenyl-3,5-hexadienoic acid ethyl ester (7a and 7b), respectively, whose structures were determined by the NMR spectral data and further chemical transformations. The reaction mechanism of the reductive rearrangement was proposed to proceed through an anion radical to form a four membered intermediate (11), which cleaved to non-conjugated dienes leading to Z and E conjugated products.

Synthese de quelques complexes tricarbonyldiene fer

Tricarbonyliron—diene complexes starting from α- or β-non-saturated alcohols and of various Diels—Alder addition products, viz. 4-vinylcyclohexene and the adduct from the dimethyl ester of acetylene dicarboxylic acid and 1-( N, N-diethylamino)-1,3-butadiene, have been synthesized. Higher yields are obtained when the starting alcohols have no allylic hydrogen atoms. The formation of complexes from non-conjugated dienes is accompanied by shifts of the most reactive double bonds.

Telomerisation par catalyse redox—VIII : Addition du tetrachlorure de carbone sur des monomeres diethyleniques non conjugues

The syntheses of 2:1-adducts from carbon tetrachloride with non-conjugated dienes were realised by redox catalysis. However, in some cases, predominant 1:1-adduct formation was observed, as well as degradation and polymerisation reactions.

Isomerization studies: III. decarbonylation of oleoyl chloride preparation of C19 dicarboxylic acids

AbstractMixtures of siomeric C17 diene hydrocarbons were obtained when oleoyl chloride was decarbonylated in the presence of a transition metal catalyst. The choice of catalyst determined the composition of diene mixture produced. Diene mixtures were characterized as a mixture of conjugated and 1,4‐ dienes, or as a mixture of isolated double bond dienes. Carboxylation of the conjugated C17 diene by hydroformylationoxidation procedure gave a C18 monocarboxylic acid as the major product, whereas with nonconjugated C17 diene, the major product was a C19 dicarboxylic acid. Application of the Koch carboxylation procedure to C17 diene mixtures gave a C19 dicarboxylic acid mixture as the major product. This latter acid mixture was structurally different from diacids obtained from the hydroformylation‐oxidation procedure.

ChemInform Abstract: CHEMISTRY OF THE PODOCARPACEAE PART 53, REARRANGEMENT OF A TETRASUBSTITUTED EPOXIDE

AbstractBei der durch Bortrifluoridätherat induzierten Umlagerung des aus dem Podocarpatrienol (I) über das Podocarpenol (II) erhältlichen Epoxids (III) entstehen das Abeopodocarpanon (V) und das Abeopodocarpanol (VI).

Reactions of palladium(II) halides with 7-methylenebicyclo[2.2.1]hept-2-ene derivatives; unique trans-halogenopalladation of the exocyclic double bond

7-Methylenebicyclo[2.2.1]hept-2-ene and its derivatives are unusual in that the two double bonds are crossed. In contrast to the behaviour of most non-conjugated dienes toward palladium(II), these dienes do not form stable chelated diolefin complexes. Instead, in solvents of low polarity, halogen-bridged dimeric 2–3η-{(bicyclo-[2.2.1]hept-2-en-7-yl)methyl} chelates are formed, in which C(7) is bound to either Cl, Br, or MeO (the latter if methanol is present in the reaction mixture). In the absence of methanol, the very fast overall reactions involve trans-addition of palladium and halogen to the exocyclic olefin, with co-ordination of the remaining double bond. The trans-addition must occur either by an ionic or a bimolecular path. In any event the facility for trans-halogenopalladation observed here suggests that cis- and trans-halogenopalladations of organic substrates may in general be competitive.

Through-space interaction in non-conjugated acyclic dienes studied by photoelectron spectroscopy

The He (I) PE-spectra of the non-conjugated acyclic dienes 1 (n), n = 5, 6, 7, 8, 9 are reported. The π-level splitting in the molecules amounts respectively to 0·34, 0·46 (or 0·31), 0·41, 0·21 and 0·14 eV. Arguments based on the observed fine structure of the first two bands suggest there is no crossing of the π-levels, and EHT calculations on different conformations of 1 (5) and 1 (6), as well as comparisons with other available data, indicate a through-space dominated interaction throughout the series 1 (n).

Solution photochemistry. X. Effects of double-bond geometry and of increasing double-bond separation on the photochemical reactions of acyclic nonconjugated dienes

Solution photochemistry. X. Effects of double-bond geometry and of increasing double-bond separation on the photochemical reactions of acyclic nonconjugated dienes

Reaction of diphenylmethylene with non-conjugated dienes

Reactions of the triplet carbene, diphenylmethylene, with the non-conjugated annular dienes, norbornadiene and cyclo-octa-1,5-diene, have been studied in the hope of achieving transannular addition which might give useful synthetic entry into bridged systems. New compounds were obtained but there was no evidence for the presence of any transannular adducts.

Selective hydrogenation with copper catalysts: I. Isolation and identification of isomers formed during hydrogenation of linolenate

AbstractMethyl linolenate was hydrogenated with 10% copper chromite catalyst at 150 C and atmospheric hydrogen pressure. The product was separated into monoene, diene and triene fractions by countercurrent distribution. These fractions were further separated into various geometrical isomers. The double bond location in the various fractions was determined by reductive ozonolysis. Double bonds in bothcis andtrans monoene fractions, as well as incis,trans andtrans,trans conjugated dienes, were extensively isomerized. A monoene containing vinylic unsaturation was one of the major products. The nonconjugated dienes were mostly dienes whose double bonds were widely separated. Results are explained on the basis of conjugation of the double bonds in linolenate followed by hydrogen addition.

Triterpenes of the friedelane series. VII. The structure of Friedelan-x-one

The photolysis of 3β-hydroxyfriedelan-α-one results in the loss of acetaldehyde from ring E and the formation of a non-conjugated diene. The structure of this diene is established and its formation allows the location of the α-oxo group to be assigned to C21.

Alkyl-transition metal compounds V. n- And sec-alkylchromium systems: Reaction with dienes

Tri-n- and -sec-butylchromium react with conjugated and non-conjugated dienes to give hydrogenation and isomerization products. The former arise by hydrogen transfer processes within the alkylchromium/diene complex. The latter are geometric and positional isomers of the starting dienes. The alkylchromium systems are thus excellent catalysts for the selective rearrangement of linear dienes.

Coupling of allylic halides promoted by iron metal dispersed in dimethyl formamide

The coupling reaction of allylic halides to produce non-conjugated dienes was investigated. It was found that iron powder could be utilized, without any special pretreatment, to promote the coupling reaction when a dipolar aprotic solvent was employed as the reaction medium.Effects of variables such as the nature of the halogen atom in the reactive position of the substrate, substituents on the substrate, presence or absence of organic or inorganic halide catalysts, and solvent type were explored briefly.Non-conjugated dienes can be prepared in yields which exceed 90% in the more favorable cases. The present procedure avoids many of the difficulties inherent in such previous methods as the Grignard reaction or the nickel carbonyl-promoted reaction.

Free-radical addition reactions of some olefins related to bicyclo[2,2,2]octane

The products of the addition of benzenethiol to bicyclo[2,2,2]oct-2-ene, 2-methylenebicyclo[2,2,2]octane, 5-methylenebicyclo[2,2,2]oct-2-ene, 2,3-dimethylenebicyclo[2,2,2]octane, 5,6-dimethylenebicyclo[2,2,2]oct-2-ene, and 8,9-dimethylenebicyclo[3,2,2]non-6-ene have been investigated. The additions of methanethiol to 2,3-dimethylenebicyclo[2,2,2]octane, of p-thiocresol to 5,6-dimethylenebicyclo[2,2,2]oct-2-ene, and of bromotrichloromethane and methylene dibromide to bicyclo[2,2,2]oct-2-ene have also been studied. In the additions to mono-olefins, products of 1,2-addition to the double bond result, whereas with conjugated dienes products of 1,4-addition to the diene systems are formed. Only a few per cent, at most, of products of homoconjugative addition were isolated in the addition of benzenethiol to 5-methylenebicyclo[2,2,2]oct-2-ene. No such product was detected in additions to 5,6-dimethylenebicyclo[2,2,2]oct-2-ene and 8,9-dimethylenebicyclo[3,2,2]non-6-ene. The double bonds and diene systems in these compounds react independently of each other to a large extent. The reactivities (relative to oct-1-ene) of the olefins and dienes in the bicyclo[2,2,2]octane series towards benzenethiol, and towards methyl thioglycollate have been obtained. Apart from the conjugated dienes, which have high reactivities, the olefins and non-conjugated diene are less reactive than the corresponding compounds related to norbornene. This may indicate the smaller degree of strain in olefins in the bicyclo[2,2,2]octane series.