Cyclooctadienes, decomposition

A remarkably stable, deep red Ni° stannylene complex, [Ni(1068)4l, has been prepared by the reaction of [Ni(l,5-cyclooctadiene)2] with (1068) in toluene at —78 °C. 70 In spite of the bulkiness of (1068) and the known tendency of analogous Ni° phosphine complexes to dissociate in solution, [Ni(1068)4] remains intact in solution and, moreover, melts at 178-180 °C without decomposition. X-ray crystallography shows tetrahedral geometry about the nickel atom, with Ni—Sn bond lengths of 2.3898(2)-2.399(2) A. 

This solution of iodosobenzene, acetic acid, and cis,cis-l,5-cyclooctadiene should continue to be stirred and should not be allowed to react for more than 20 hr (at refluxing temperature) to prevent decomposition of the product diacetate. 

For the aziridination of 1,3-dienes, copper catalysis gave better yields of A-tosyl-2-alkenyl aziridines with 1,3-cyclooctadiene, 1,4-addition occurred exclusively (50%) [46]. Good results were also obtained on rhodium catalysed decomposition of PhI=NNs (Ns = p-nitrophenylsulphonyl) with some alkenes the aziridination was stereospecific, whereas with chiral catalysts asymmetric induction (up to 73% ee) was achieved. However, cyclohexene gave predominantly (70%) a product derived from nitrene insertion into an allylic carbon-hydrogen bond [47]. 

The alicyclic vinyl halide 1-iodocyclooctene yields not only the direct nucleophilic trapping product 86 (and its acid-catalysed decomposition product 87) but also 88 and 89 (equation 74)291, which are produced via 1,2-cyclooctadiene as intermediate, as demonstrated by deuterium labelling for a related vinyl iodide. Deprotonation of the photogenerated vinyl cation is clearly more efficient than nucleophilic trapping in methanol. A... 

Dibromo(l,5-cyclooctadiene)platinum(II) is a very pale yellow, air-stable solid. The solubility of the compound is similar to that of the chloro derivative except that the rate of decomposition in dimethyl sulfoxide is appreciably faster. The p.m.r. spectrum of the compound in chloroform shows resonances at 4.32r, Jpt-H = 70 Hz., for the olefinic protons and 7.43r for the methylene protons. The infrared spectrum in Nujol has strong absorption maxima at 1334, 1175, 1007, 870, 830, and 780 cm. 1. 

Vlcek showed polarographically that the decomposition of Co2(CO)8 in ethanolic solution in the presence of ligand has, as the rate-determining step, the formation of Co2(CO)7L (703). Where C = Mo(CO)4, Y = 1,5-cyclooctadiene, and Z = bipy or phen, the k term is believed to correspond to bond fission as the rate-determining step (i.e., Because of the value of the entropy of activation and the variation of 2 with Z,... 

Thermal Decomposition of Sodium Trichloroacetate Reaction of Dichlorocarbene with 1,5-Cyclooctadiene... 

The decomposition of adducts of 1,5-cyclooctadiene to give 3.3.0-octanes has precedent. Thus, Anderson and Burreson (5) decomposed the oxymetallation adduct by light to give an unsaturated bicyclooctane, whereas Takahashi and Tsuji (253) used strong base to produce a disubstituted bicyclooctane. Both reactions must also occur by addition of Pd(II)-C bonds across the second olefinic bond as in Eqs. (205) and (206). 

Even though the second double bond provides some stabilization, resistance of the compounds to decomposition by Pd(II)-assisted hydride transfer is interesting. Thus, Pd (II) alkyls with -hydrogens even when they have phosphine groups (which would be expected to be better than olefin groups in stabilizing Pd(II) alkyls) decompose rapidly. As recently discussed by Stille and Morgan (39), the stability of the adducts from bicyclic olefins such as the one from dicyclopentadiene (Reaction 72) can probably be reasonably attributed to the fact that Pd( II)-hydride elimination would form a strained double bond. However, the stability of the adduct from 1,5-cyclooctadiene cannot be explained in this way. 

Borabicyclo[3.3.1]nonane (9-BBN) has been prepared by the thermal redistribution of 9-n-propyl-9-BBN, and the hydroboration of 1,5-cyclooctadlene with borane-tetrahydrofuran complex followed by thermal isomerization of the mixture of dialkylboranes at BS C. Solutions of 9-BBN have been prepared from the hydroboration of 1,5-cyclooctad ene with borane-methyl sulfide in solvents other than THF.6 The present procedure involves the cyclic hydroboration of 1,5-cyclooctadiene with borane-methyl sulfide in 1,2-dimethoxyethane.7 Distillative removal of the dimethyl sulfide in this special solvent system provides a medium that gives high purity, large needles of crystalline 9-BBN dimer in excellent yield. The material can be handled in air for brief periods without measurable decomposition. 

Diene)Mn(CO)3 anions are stable in solution, and have been characterized by infrared and NMR spectroscopy. However, exposure of the anion solution to oxygen results in decomposition to give the free ligand. Reduction of (crotyl)Mn(CO)4 (62) gives the manganese-carbonyl transfer reagent ( -2-butene)Mn(CO)4. Reaction of 1,3-cycloheptadiene, 1,3-cyclooctadiene, 1,3,5-cycloheptatriene or 1,3,5,7-cyclooctatetraene... 

The complex bis(l,5-cyclooctadiene)nickel(0) is obtained as yellow crystals which sublime in vacuo at 90°C and melt with decomposition at 142°C. The infrared (73) and NMR sj)ectra (419) indicate that all double bonds are coordinated to the nickel atom (i.e., Ni is 4 - coordinate) the C=C bands at 1656 and 1490 cm in the free diene are replaced by a strong band at 1328 cm in the complex, while the NMR spectrum shows only two signals (intensity ratio 1 2) at t = 5.64 (olefinic protons) and T = 7.84 (methylene protons). The absence of a center of symmetry (infrared) suggests that configuration (195b) is more probable than (195a), indicating a tetrahedral rather than square planar coordination... 

Decomposition of the CU2X2 complexes left as residues from such illuminations produced cis,cis-1.5-cyclooctadiene, cis,trans-1.5-cycloocta-diene, and small amounts of trans,trans-1.5-cyclooctadiene (33). (33) gives (32) on illumination 522>. However, is it not yet clear whether free (33) is formed in cyclooctadiene photolysis, and then undergoes rear-... 

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