C«-Cyclooctene

Pibenzo[a,c]cyclooctene 35 has been known since 1963. In a continuation of my interest in dehydro[8]annulenes, the conversion of 35 to the bis-alkyne 36 was also attempted. However, it was apparent that the presence of the 1,3-diyne unit, together with the expected peri-H-H interaction, would render the planar 36 highly... 

The oxidation of c -cyclooctene with basic permanganate illustrates the new method. The octene (0.1 mole) in methylene chloride is treated with a 40% aqueous solution of sodium hydroxide and I g. of benzyltricthylammonium chloride. The mixture is cooled to 0° and KMnO (0.1 mole) is added in small portions over 2 hr. with vigorous stirring after standing overnight at 0°, the precipitated MnOj is dissolved by S02- The rii -l,2-cyclooctanediol is isolated by ether extraction and crystallization in 50% yield. The yield of diol obtained without a phase-transfer catalyst is 7%. ... 

Liu, K.T., Lesca, P. Pharmacological properties of Dibenzo (a,c) cyclooctene derivatives isolated from fructiis Schizandra chinensis III. Inhibitory effects on carbon tetrachloride-induced lipid peroxidation, metabolism and covalent binding of carbon tetrachloride to Hpids. Chem. Biol. Interact. 1982 41 39-47... 

Epoxidation takes place preferentially or more rapidly at electron-rich (i.e., tetraalkylated) double bonds [217]. The reaction is stereospeciflc cis alkenes give cis epoxides, and trans alkenes give trans oxides [211. 1,2-Dimethylcyclopentene is oxidized with peroxybenzoic acid to 1,2-di-inethylcyclopentene oxide in 85% yield [296], and dj-cyclooctene is transformed by hydrogen peroxide into c -cyclooctene oxide in 60-61% yield [1099]. 

A synthetic bromine derivative ofgomisin J [(6/ ,7 SVV-biar)-4,9-dibromo -3,10-dihydroxy-1,2,11,12-tetramethoxy-6,7-dimethyl-5,6,7,8-tetrahydrodi-benzo[a,c]cyclooctene], was found to be a potent inhibitor of the cytopa-thic effects of HIV-1 on MT-4 human T cells (ED50, 0.1 to 0.5 pM). Comparison of various gomisin J derivatives with gomisin J itself showed that iodine, bromine, and chlorine in the fourth and ninth positions increased RT inhibitory activity as well as cytoprotective activity [161],... 

Cyclooctanol Cyclooctanone 1,3,5,7-Cyclooctatetraene 1,3,5-Cyclooctatriene c/>Cyclooctene frans-Cyclooctene Cyclooctyne... 

Ionization potential of Continued) butenone, 123 cyclic diacetylenes, 305 cyclohexene, 48, 102 c -cyclooctene, 102 frans-cyclooctene, 102 DABCO, 81 dimethyl ether, 123 ethylene, 80, 319 formaldehyde, 123, 319 hydrogen atom, 55, 75 methanol, 123 methyl acetate, 123 methyl acrylate, 123 nitrous oxide (N2O), 172 norbornadiene, 48 norbornene, 48 oxetane, 123 tetrahydrofuran, 123 trimethylamine, 81 water, 123... 

As seen from Table I, the heats of formation (AH2) of the Mn-SBu2 bond and the Mn-cw-cyclooctene bond were found respectively, to be -29.1 2.0 and -24.5 2.3 kcal/mol. Thus, we expected the Mn-SBu2 bond to be 4.6 3.0 kcal/mol stronger than the Mn-c -cyclooctene bond. To confirm this prediction, we examined the equilibrium shown below between the corresponding manganese complexes. 

Figure 3. Plot of kobs [Ligand] for the reaction of CpMn(CO)2S with ds-cyclooctene and Bu2S at 25 TC in /i-heptane. For c -cyclooctene, r2=0.93 for Bu2S, r =0.996. Other data is given in Table I. Error bars are the greater of the standi deviation calculated from the scatter in the data and 10%.

Under a nitrogen atmosphere, a solution of 2.11 g benzophenone (11.6 mmol) and 3.83 g c/ -cyclooctene (34.8 mmol) in 300 mL petroleum ether at was irradiated in a Rayo-net photoreactor at 350 nm for 24 h. A white precipitate (350 mg) was formed during the irradiation, which was collected by filtration and identified as 1,1,2,2-tetraphenylethanediol (benzpinacol) by and C-NMR spectroscopy. Distillation of the solvent and most of the residual olefin at 50°C (10 mbar) afforded 3.66 g yellow oil, which contained both diastere-omeric oxetanes (cis/trans 40 60 by NMR spectroscopy). The crude product mixture (1.83 g) was purified by silica gel column chromatography with Et20/petroleum ether (1 10) as the eluent to afford 256 mg c/5-10,10-diphenyl-9-oxabicyclo[6.2.0]decane as a colorless oil, in a yield of 15%. In addition, 285 mg tran -10,10-diphenyl-9-oxabicyclo[6.2.0]decane was obtained as a colorless oil, in a yield of 17%. Further purification of each diastereomers was carried out by bulb-to-bulb distillation (Kugelrohr) at lOO C (0.03 mmHg). 

Heterogeneous Mn(III) porphyrin [63] and Mn(III) chlorin [65] covalently immobilized on silica (Fig. 5.6) were used in the oxidation of c -cyclooctene (19). The efficiency of the immobilized Mn( -N02TEXZ PP)C1 was evaluated under several conditions, and the best performance was achieved when a lower volume of solvent and a lower rate of oxidant addition were used. In this case, 89% of conversion was obtained after 21 h at 20 °C. The recovered catalyst was reused, but affording only 5% of substrate conversion. Nevertheless, by increasing the catalyst amount to a ratio SjC of 100 instead of 600, the... 

We have taken advantage of the ease of generating Ru-NHC complexes in situ to help define structure-activity relationships for imidazolin-2-ylidene and imidazolidin-2-ylidene derivatives used as ancillary ligands in metathesis catalysts. For this purpose, a wide range of new imidazolium and imidazoli-nium chlorides bearing aromatic substituents was synthesized. These ionic precursors were deprotonated with potassium tert-butoxide or sodium hydride and combined wMi [RuCl2(p-cymene)]2 in chlorobenzene at 60°C. Cyclooctene was then added and its polymerization was allowed to proceed for 2 h under visible light illumination (Eq. 3)." ... 

The presence of the carbomethoxy and ttifluoromethyl groups in (he diene system of the pyrone 87 inaeases its electrophilicity and its ability to undergo Diels-Alder reactions with inverse electron demand. The reaction of 87 with l-(A(-pytrolidino)-l-cyclopentene at 30 C gives rise to the tricyclic lactone 88. When 88 is treated with HCl/dioxane, (he indane derivative 89 is obtained. This compound was prepared directly in the reaction of 87 with l-(trimethylsilyloxy)cyclopentene at 180 °C in 90 % yield. More reactive tetramethoxyethylene adds at 100 °C to 87 to afford 90. With 2,5-dihydrofiiran at 130 °C, 91a is formed as the sole isomer. Endo-adducts of this type result also with cyclopentene (91b, 120 °C), cyclooctene (91c, 150 °C), and indene (91d, 80 C). All four possible regio- and stereoisomers can be identified in the reaction of 87 with vinylacetate at 150 °C (79 % yield) (Scheme 28). 

The rearrangement of 9-lithiated 9,14-dihydrotribenzo[a,c,/ cyclooctene to 9-(o-tolyl)-9-fluorenyllithium implies a formal [l,4]-migration. In reality the isomerization is brought about in a two-step addition/elimination sequence and the ultimate connectivity is dictated by the thermodynamics. 

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