Cyclo-octa-1,5-diene

Unsubstituted monocyclic di- or multi-olefins, e.g. cyclo-octa-1,5-diene. 

In 1980 the Goodyear company announced copolymers of cyclopentadiene, cyclo-octene or cyclo-octa-1,5-diene with the Diels-Alder addition product of hexachlorocyclopentadiene and cyclo-octa-1,5-diene. This material has been proposed as an alternative to the polychloroprenes, with lower ( 5°C), and superior ozone resistance... 

Cyclopentene, cyclohexene, and cycloheptene were obtained by intramolecular oxidative couplings of the bis-ylides (161 n = 3, 4, or 5) but oxidation of (161 n = 2) gave cyclo-octa-1,5-diene. Oxidation of the bis-ylide (161 n — 8) gave cyclic polyenes containing 20, 30, 40, 50, and 60 atoms. 

Olefinic compounds such as a-pinene (309) and /Dpi none (312) undergo hydrogen abstraction followed by rearrangement and amino-oxyl insertion (310, 313) and addition reactions (311, 314, 315), as shown in reactions 43 and 44627. Other olefinic compounds such as norbomadiene, cyclo-octene and cyclo-octa-1,5-diene gave analogous results628. 

The insoluble complexes (27) have been prepared by the room-temperature reaction of the appropriate cyclo-octa-1.5-diene cuprous halide dimer with [(Tt-CpljTilSR),], in toluene, under an atmosphere of nitrogen. The existence of a Ti—Cu bond is suggested from comparative spectral studies with [(7t-Cp)2-... 

The above type of bonding is assumed to occur in other metal-olefin and metal-acetylene complexes (172). Acetylenes have two mutually perpendicular sets of ir-orbitals and are therefore capable of being bonded to one or to two metal atoms both types of complexes are known. When the hydrocarbon is a nonconjugated polyolefin e.g., cyclo-octa-1,5-diene, each C C bond interacts independently with the metal atom. In complexes of conjugated polyolefins, e.g., cyclopentadiene, infrared and nuclear magnetic resonance studies (99) indicate that it is not yet possible to distinguish between structure (IV), in which each C C bond independently contributes two --electrons to the metal-olefin bonding, and structure (V), in which... 

Chelating polyolefins displace carbon monoxide from chromium hexa-carhonyl to form stable olefin complexes. Thus cyclo-octa-1,5-diene gives the yellow complex [Cr(CO)4(C8H12)] for which the cfs-structure (VI M = Cr) is proposed (79). 

Dienes react with molybdenum hexacarbonyl to give complexes of the type [Mo(CO)4(diene)] and [Mo(CO)2(diene)2], which are generally yellow, soluble in organic solvents, and readily sublimed. Cyclo-octa-1,5-diene (12, 79, 151), bicyclo[2,2,l]hepta-2,5-diene (175), a dimer of cyclo-octa-tetraene (12) and dimethyldivinylsilane (158) give the former type of complex with the structure (VI M = Mo), while butadiene (81) and cyclo-hexa-1,3-diene form the latter type (80). Tetracyclone gives the complex [Mo(CO)2(tetracyclone)2] (215). 

Diene complexes of the type [W(CO)4(diene)l (VI M = W) are formed by cyclo-octa-1,5-diene (79, 151), hexa-1,5-diene (151), and dimethyldi-vinylsilane (158) on heating with tungsten hexacarbonyl. Cycloheptatriene (158) displaces cyclo-octa-1,5-diene and 1 mol. of carbon monoxide from its tungsten complex ... 

The hydrocarbon complexes of tungsten have been arranged in the following order of stability (158) hexamethylbenzeuc > p-cymene > eyclo-octa-1,5-diene > hexa-1,5-diene p-cymene > dipentene and cyclo-hep-tatriene > cyclo-octa-1,5-diene. 

The strongly chelating dienes bicyclo[2,2,l]hepta-2,5-diene (1) and cyclo-octa-1,5-diene (12) react with ruthenium halides to give stable, diamagnetic complexes of the composition [RuX2(diene)] (X = Cl, Br, I). Note added in proof. 

Osmium (IV) does not react with ethylene under pressure (97), or with cyclo-octa-1,5-diene (45), but the osmium(II) complex [Os2Cl3(PEtPh2)6]Cl gives the stable, 6-coordinated complex [OsCUfPEtPl MCsHu)] on treatment with cyclo-octa-1,5-diene, which acts as a chelating ligand in the complex (40a). 

No complex was obtained on treatment of iridium (III) chloride with ethylene (67, 97, 138) or cyclo-octa-1,5-diene (45), but the ethylene complex [IrCl2(C2H4)] was reported to be formed by the action of ethanol on iridium chloride (67,138). No further examination of this complex has been reported. 

Chelate complexes of the type [PdX2(diene)] (X = Cl, Br) are readily formed by the dienes hexa-1,5-diene (124), bicyclo 2,2,lJhepta-2,5-diene (1, 7) tricyclo[4,2,2,0]-deca-triene and -diene derivatives (10), cyclo-octa-1,5-diene and dicyclopentadiene, but not dipentene (43). These may be converted to complexes of the types [Pd2X2(dieneOR)2] and [PdCl(dieneOR)-(amine)] (R = alkyl) (43), and their properties indicate that they have similar structures to the platinum complexes (XXXI) and (XXXIII). 

The dienes bicyclo[2,2,l]hepta-2,5-diene 1, 7), cyclo-octa-1,5-diene 43), dicyclopentadiene 43, 68), dipentene 48), hexa-1,5-diene 43, 124) and diallyl ether 124) form complexes of the type [Ft X2(diene)J (X = halogen). These complexes are monomeric and nonconducting, and are formulated as chelate complexes of type (XXXI) in which the diene, represented by the symbol (XXXII) functions as a bidentate ligand and occupies two... 

Anhydrous silver-olefin complexes are readily dissociable, low-melting, and variable in composition 92a, 176, 183). Cyclic olefins and polyolefins form stable complexes with silver nitrate or perchlorate, but again the Stoichiometry of the complexes varies considerably, sometimes depending on the conditions of preparation. The following types have been isolated [Ag(un)2]X (un = e.g., cyclohexene, a- and /3-pinene) ISO), [Ag(diene)]X diene = e.g., dicyclopentadiene 220), cyclo-octa-1,5-diene 50, 130), bi-cyclop, 2,1 ]hepta-2,5-diene 207), and cyclo-octa-1,3,5-triene 52), and [Ag2(diene)]X2 (diene = e.g., cyclo-octa-1,3- and -1,4-diene 180), bi-cyclo[2,2,l]hepta-2,5-diene 1) and tricyclo[4,2,2,0]-decatriene 10)). Cyclo-octatetraene (cot) forms three adducts with silver nitrate 52), viz., [Ag(cot)]NOs, [Ag(cot)2]N03, and [Ag3(cot)2](N03)3. On heating, the first two lose cyclo-octatetraene and all three decompose at the same temperature. From the stoichiometry of the above complexes it appears that the... 

New total syntheses9 of azabicyclo[4.2.1]nonanone (10) have now been elaborated. The first synthesis started with 5-azidocyclo-oct-l-ene (7). Reduction and iV-methylation (via the urethane), followed by treatment of the secondary amine with hypobromous acid and with base, gave a mixture of 9-methyl-9-azabicyclo[4.2.1]nonan-2a-ol (8) and its 2/3-isomer (9), contaminated with some azabicyclo[3.3.1]nonane analogue cf. (18). The second synthesis starts with the monoepoxide from cyclo-octa-1,5-diene (11). Treatment with methylamine and... 

S-Donor ligands. New complexes of the ligand SC6C15 have been isolated using Scheme 11 (L = CO L2 = cyclo-octa-1,5-diene, norbornadiene, Cp2).140 Related,... 

CO)3] (R = H or Pz) complexes via carbonylation of [Rh(RBPz3](L L)] (L-L = C2H4 cyclo-octa-1,5-diene) substrates.146 Oxidation of this product with iodine in dichloromethane yielded the deep red Rh111 derivative [Rh(RBPz3)I2(CO)], which n.m.r. evidence showed to be an (i3-polypyrazolylborate complex. 

Higher 43-hydrocarbyl derivatives of transition metals can be obtained by partial protolysis of the bis(7i-allyl)metal compounds formed from cyclo-octa-1,5-diene metal complexes and 1,3-butadiene with one equivalent of the Bronsted acid in the presence of the proper ligand in a polar solvent at lowered temperature (e.g. — 40°C). For instance, Ni [43-(CxHn)l and Ni—[43-(Ci2Hig)] derivatives have been yielded by the reaction of Ni(CxH 2)2 [(Ni(Cod)2] with 1,3-butadiene (C4H6), followed by treatment with a Bronsted acid, according to scheme (1) [132] and scheme (2) [37] respectively ... 

Two dialkyl boranes arc in common use. The bicyclic 9-borabicyclo[3.3.1] nonane (9-BBN), introduced in Chapter 34 as a reagent for diastereoselcctive aldol reactions, is a stable crystalline solid. This is very unusual for an alkyl borane and makes it a popular reagent. It is made by hydroboration of cyclo-octa-1,5-diene. The second hydroboration is fast because it is intramolecular but the third would be very slow. The regioselectivity of the second hydroboration is under thermodynamic control. 

M. Green, J. A. K. Howard, J. L. Spencer, and F. G. A. Stone, Synthesis of Ethylene, Cyclo-octa- 1,5-diene, Bicyclo [2.2.1]heptene, and trans-Cyclo-octene Complexes of Palladium ) and Platinum(O) Crystal and Molecular Structure of Tris(bicyclo2.2.1]hepte-ne)platinum, J. Chem. Soc., Dalton Trans. 1977, 271-277. 

A serendipitous discovery(6) that [Pt(cod)2] (cod cyclo-octa-1,5-diene) reacted with perfluoropropene to give the diplatinum complex [pt2 y-C(CF3)2 (cod)2], rather than the simple Ti2 adduct [Pt(CF2 CFCF3)(cod)], led to the idea(7) that mononuclear metal-carbene or -carbyne complexes would combine with nucleophilic and co-ordinatively unsaturated metal species (M") ... 

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