Chalcones oxidation

C. Morisseau, G. Du, J. W. Newman, B. D. Hammock, Mechanism of Mammalian Soluble Epoxide Hydrolase by Chalcone Oxide Derivatives , Arch. Biochem. Biophys. 1998, 356, 214 - 228 C. Morisseau, M. H. Goodrow, D. Dowdy, J. Zheng, J. F. Greene, J. R. Sanborn, B. D. Hammock, Potent Urea and Carbamate Inhibitors of Soluble Epoxide Hydrolases , Proc. Natl. Acad. Sci. U.S.A. 1999, 96, 8849 - 8854. 

An account has also been given of the reaction between benzylmercaptan and cis-benzene trioxide.With a-mercapto esters, p-substituted phenyloxiranes undergo normal opening, without being affected by the substituents on the benzene ring. Chalcone oxides react with mercaptan with accompanying C-C bond cleavage (Eq. 308). ... 

Not only Cc,-0 and rarely Cg-O bond breaking but C -Cg bond splitting may be observed. A consequence of this is the very stereoselective epimerization of benzylidenecyclohexanone oxide.The stereochemistry of photolysis of optically active dypnone oxide has been studied and the possibility of C-C bond cleavage has likewise been proposed.C-C bond splitting has also been observed during examinations of chalcone oxides transformation to dibenzoylmethane, trans-cis isomerization, and photofragmentation occur via ylides and acylcarbene intermediates (Eq. 341). ... 

Morisseau C, Du G, Newman JW, Hammock BD. Mechanism of mammalian soluble epoxide hydrolase inhibition by chalcone oxide derivatives. Arch Biochem Biophys 1998 356 214-28. 

In another approach, epoxidation of chalcone and substituted chalcones by TBHP was catalyzed by a calcium-BINOL complex bearing a poly(ethylene glycol) chain in 6-position [97]. Chalcone oxide yields between 92 and 95% were obtained with ee values ranging from 40 fo 47% using a catalyst loading of 10 mol%. The pol)Tneric catalyst is soluble in the reaction mixtures and can be precipitated and recovered. Reuse in three consecutive reactions showed a continuous decrease in activity and enantioselectivity. 

Carbon suboxide, 52 Carbonylation, 148, 149, 216 Carbonyl chlorofluoride, 48, 54 Carbonyl cyanide, 60-61 N,N -Carbonyldiimidazole, 61 1,1-Carbonyldi-l,2,4-triazole, 61 N-Carbonylsulfamic acid chloride (N-Carbonylsulfamyl chloride), 61 Carboxamides, 270 Carboxamine-N-sulfochlorides, 70 p-Carboxybenzenediazonium chloride, 62 p-Carboxybenzenesulfonazide, 62 Carboxylation, 15, 16 Carboxylic acid anhydrides, 133 Carboxylic acid N,N-dimethylamines, 153 Carboxylic anhydrides, 409-410 p-Carboxyphenylhydrazones, 62 Cardenolides, 130, 131 (S-Carotene, 19 /-Carvone, 451, 452 i//-Caryophyllene, 149, 150 Catechol, 65, 233 Catechol amines, 159 Catechyl phosphorus tribromide, 63 Catechyl phosphorus trichloride, 63 Cis-Cecropia juvenile hormone, 261 Cedrene, 234, 235 a-Cedrene, 349 /3-Cedrene, 349 Cendranoxide, 234, 235 Cephalosporin C, 48 Ceric ammonium nitrate, 63-65 Ceric sulfate. 65 Cesium fluoride, 346 trans-Chalcone oxide, 422 Chalcone phenylhydrazones, 257, 258 Chalcones, 406 Chloramine, 65-66, 69 Chloranil, 66-67, 113, 116, 401,454... 

A solution of trans-chalcone oxide (fra s-l -benzoyl-2-phenyloxirane) (0.5 g) in anhydrous ether (25 ml) is heated at the b.p. with boron trifluoride etherate (5 ml) for 30 min. The mixture is then shaken with water and the a-formyldeoxybenzoin that is formed quantitatively is precipitated as copper salt. 

An extensive article on the importance of chalcone oxides in flavonoid chemistry contains 346 references. Other specialised reviews have appeared on the chemistry of juvenile hormones (up to 1974), epoxy-sulphones, and epoxyderivatives of dicyclopentadiene. ... 

Mechanism of Mammalian Soluble Epoxide Hydrolase Inhibition by Chalcone Oxide Derivatives. 

Synthetic polypeptides were found, by Julia, to epoxidize a, i-unsaturated ketones with high enantioselectivity [12], The Julih process can be easily performed at O C, and using a triphasic system comprising of toluene, water and polyalanine in the presence of alkaline hydrogen peroxide, chalcone oxide was produced in 97% ee (Scheme 1.7). The Julia process has become the method of choice for the epoxidation of fran.y-l,3-diarylenones. However, this methodology is extremely substrate-specific, and enones with enolisable a-protons are usually poor substrates. 

The asymmetric epoxidation of the chalcone type of substrate has also been accomplished using other types of chiral catalysts [15]. Wynberg was the first to use chiral ammonium salts, and obtained chalcone oxide with 55% ee using alkaline hydrogen peroxide as the stoichiometric oxidant and a quinine-derived quaternary ammonium salt as the chiral phase transfer catalyst [16]. More recently, Lygo... 

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