Arene dioxides

Boyd DR, Sharma ND, O Dowd CR, Hempenstall F (2000) Enantiopure Arene Dioxides Chemoenzymatic Synthesis and Application in the Production of Zran.s-3,4-Dihydrodiols. Chem Commun 2151... 

Arene dioxides. Arene dioxides 1 polycyclic arenes, but some identified n ides. Arene dioxides can be obtained by bond comparable to the 9,10-double bot with dimethyldioxirane (1), but in mod by this method, but can be obtained v ... 

Relatively few arene dioxides and trioxides have been reported from PAHs. Arene dioxides in the naphthalene 152, 154, 155 and anthracene 157 series have been formed in good yield by direct epoxidation of the parent hydrocarbon. These arene dioxides 152, 154, 155, and 157 were formed by MCPBA epoxidation... 

To date, the only natural product containing a benzene dioxide moiety is the antibiotic 149. In addition to this cis dioxide, there is evidence that trans naphthalene dioxide 152 may be an intermediate in the hepatic metabolism of naphthalene. The reactivity of the cis (153) and trans (152) naphthalene dioxides with nucleophiles and the relative stereochemistry of the adducts has been determined. The possibility that arene dioxide intermediates form during metabolism of PAHs has been discussed frequently. Indeed, the detection of a rrans-diol epoxide such as that derived from arene oxide 25, or the isolation of a rra s-diol oxepin (e.g., 165) is mechanistically consistent with the formation of two epoxides on either the same or different rings. However, presently available evidence would suggest that it is most unlikely that either diol metabolite was derived from an arene dioxide intermediate. Involvement of dioxide intermediates in the metabolism of PAHs will require further experimental verification. 

The epoxidation reaction of arene oxide-oxepins has been encountered in the formation of the arene dioxides of naphthalene and anthracene rings A similar approach to the synthesis of epoxides of benzene oxide-oxepin using a peroxyacid oxidant, however, was unsuccessful (Z,Z)-muconaldehyde was isolated presumably via an oxepin-epoxide intermediate. The disubstituted benzene... 

Oxidoethers. A soln. of methyl(trifluoromethyl)dioxirane in l,l,l-trifluoro-2-propanone added quickly to a stirred soln. of startg. enolether containing suspended NaHP04 as buffer at -20 to — 10° (maintaining substrate/oxidant ratio at ca. 1 1), and worked up after 4 min - product. Y 94% (by n.m.r.). There was no rearrangement (as takes place with m-chloroperoxybenzoic acid). F.e. inch epoxidation of acyclic enolethers s. L. Troisi et al.. Tetrahedron Letters 30, 257-60 (1989) arene dioxides with dimethyldioxirane s. S.K. Agarwal et al., ibid. 30, 123-6 (1989). 

Beside these free radical reactions of sulfur dioxide, its electrophilic reactions generating sulfinates with organometallic compounds453,454 or sulfinic acids with arenes under Friedel-Crafts conditions455 are well known. To complete these three-component syntheses, the sulfinates prepared first are transformed to sulfones by reactions with appropriate electrophiles, discussed earlier in this chapter, i.e. equation 82. 

An improved synthesis of 3,4-dihydro-2,l-benzothiazine 2,2-dioxide was reported by Togo and co-workers using photochemical conditions . Treatment of A-alkyl 2-(aryl)ethanesulfonamides 18 with (diacetoxyiodo)arenes under irradiation with a tungsten lamp at 20-30 °C afforded 2,1-benzothiazines 19 and 20. Chemical yields and selectivities were dependent upon the choice of solvents and the reactant s substituents 18 (Table 1). When THF and EtOH were used as solvents, the reactions failed to give the cyclized products, since their a-hydrogen was abstracted by the intermediate sulfonamidyl radical. Compound 20 was obtained as a major product when 1,2-dichloroethane was employed as a solvent. In contrast, in the case of EtOAc as solvent, compound 19 was obtained as the major product. 

Electron-transfer activation. The observation of intense coloration upon mixing the solutions of hydroquinone ether MA and nitrogen dioxide at low temperature derives from the transient formation of MA+ cation radical, as confirmed by the spectral comparison with the authentic sample. The oxidation of MA to the corresponding cation radical is effected by the nitrosonium oxidant, which is spontaneously generated during the arene-induced disproportionation of nitrogen dioxide,239 i.e.,... 

The bipyridyl-iV,iV-dioxide chromophore has been appended to a calix[4]arene to give L50, and complexed with europium and terbium... 

Prodi, L. Pivari, S. Bolletta, F. Hissler, M. Ziessel, R. Synthesis of functionalized calix[4]arene ligands incorporating bipyridine N.N -dioxide chromo-phores and luminescence of their lanthanide complexes. Eur. J. Inorg. Chem. 1998, 1959-1965. 

Our body, like any machine, requires a source of fuel. We talk, we breathe, we eat, and sometimes we even think. All of it requires energy, and this we get from burning food. Not in a furnace, but in our cells. As the food burns — that is, as it converts to carbon dioxide and water — it releases energy to maintain body temperature and to power all of our activities. If, on the one hand, we eat but aren t very active, the unused fuel piles up, and we put on weight. If, on the other hand, we don t take in enough fuel, the body switches to burning its stored supplies, and we lose weight. Pretty simple. 

Why aren t atmospheric levels of carbon dioxide rising as rapidly as might be expected based on the increased output of carbon dioxide resulting from human activities ... 

Z1220 (351) is shown to have a benzene dioxide structure.194 Likewise, metabolites 352195 and 353196 from Verongia sponges were postulated to have been biosynthesized through arene oxides. 

Keywords arenes, nitrogen dioxide, nitration, gas-solid reaction... 

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