Cyclooctatetraene oxidation reactions

Exercise 22-41 Write reasonable mechanisms for the different oxidation reactions of cyclooctatetraene with mercuric ethanoate in ethanoic acid, methanol, and water solutions. Notice that compounds of the type Hg(OR)2 appear to act in some cases as OR-donating agents and also that the oxide produced from cyclooctatetraene and peroxyacids (Section 15-11C) rearranges readily in the presence of acids to phenylethanal. 

The intermediacy of an a-lithiated oxirane was postulated for the first time by Cope in the 1950s while studying the reaction of cyclooctatetraene oxide with hthium diethylamide (1951JA4158, 1960JA6370). Since then, and particularly over the last 10 years, many synthetic methodologies have... 

The addition of benzonitrile oxide to cyclooctatetraene produced a monoadduct which was induced to undergo valence tautomerism to produce a tricycloisoxazoline (Scheme 104). A similar reaction with tropone gave a minimum of eight adducts from which two monoadducts were isolated (Scheme 104) (70T5113). 

Few 1 -benzothiophene-S-oxides 218 were obtained in moderate yields by treatment of 1-arylacetylenes 219 with sulfur dioxide and benzene in the presence of antimony pentafluoride250 (equation 127). A series of cyclic sulphoxides have been prepared by hydrolysis of the corresponding alkoxy sulphonium salts 220251-254 (equation 128). Syn-sulphoxide 221 was obtained in a low yield (15-20%) in the reaction of the dianion of cyclooctatetraene 222 with thionyl chloride255 (equation 129). 

Eight-membered heterocyclic systems embrace a very broad variety of compounds ranging from cyclic ethers and imines to highly labile analogs of cyclooctatetraene, and the properties and chemical behavior of these compounds of course depend entirely on the extent and location of unsaturation. For this reason, preparative methods and reactions are treated together for each ring system and oxidation level. 

Two syntheses of Rh4(CO)i2 at ordinary pressure have been developed 81, 279 making this compound easily available, and CO scrambling in this molecule has been carefully examined 110,112,164. Strong nucleophiles including CO at high pressure destroy the Rh cluster 45, 396, but with phosphines of limited donor strength, with cyclooctatetraene, and with acetylenes up to four CO groups could be replaced with retention of the Rh4 unit 45, 247, 396. Rh4-like Rhg-clusters show catalytic activity (7 04, 364 which has been used for hydroformylation 88 and oxidation (297) reactions. 

The 18 n-electron system furo[3,4-c]octalene (356) is available by a Wittig reaction starting from cyclooctatetraene-1,2-dicarboxaldehyde it is obtained as an unstable pale yellow liquid, which is rapidly oxidized in air. The electronic spectrum resembles that of 353, showing little extended conjugation. Compound 356 underwent Diels-Alder addition at the terminal cyclooctatetraene ring thus treatment with dimethyl fumarate leads to monoadduct 357. ... 

By use of a similar method other more stable 1-substituted phosphiranes are prepared, 1-phenylphosphirane (123) being the most stable. When the cyclooctatetraene dianion is treated with dichlorophenylphosphine the bicyclic 1-phenylphosphirane derivative (124) is formed. At 70 °C in CHC13 it rearranges into the bicyclic phosphabicyclo[4.2.1]heptane derivative (125). Oxidation and photochemical reaction give the tricyclic phospholene 1-oxide derivative (126 equation (76)) (66JA3832). 

The first detailed study of the individual steps of the cationic pathway of the intramolecular Heck reaction was recently described by Brown (Scheme 8G.21) [46], Oxidative addition of aryl iodide 21.1 to [l,l -bis(diphenylphosphino)ferrocene](cyclooctatetraene)palladium generated 21,2. Complex 21.2 was stable at room temperature and was characterized by X-ray crystallography no interaction between the palladium center and the tethered alkene was observed in this intermediate. Treatment of 21.2 with AgOTf at -78°C removed iodide from the palladium coordination sphere, which facilitated a rapid alkene coordination and subsequent... 

The synthesis and preliminary X-ray structure of the first organometallic Ce(IV) complex Ce(CsH8)2 was reported in 1976 [115] and reproduced in 1985 [116] by the reaction of cerium(IV) isopropoxide with triethylaluminum in the presence of cyclooctatetraene, as shown in Figure 8.35. The accurate sandwich molecule structure of cerocene has been eon-firmed by an X-ray structural study on the methyl substituted cerocene [Ce(MeCOT)2] [117], Subsequently, two more substituted cerocene analogs have been synthesized via a more efficient method, for example, controlled oxidation of cerium(III) precursors and one of these complexes has been structurally characterized [118],... 

Moreover, in the same work, the 0-labeling experiment confirmed chiral dioxiranes to be the intermediates in chiral ketone-catalyzed epoxidation reactions. Murray et al. reported the synthesis and structural characterization of cyclooctatetraene tetraepoxides 90 and 91 through the oxidation of cyclooctatetraene with excess of DMDO lb... 

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