Oxidative activation dime

The reaction of 1,2,4-triazine 4-oxides 55 with CH-active 1,3-diketones (dime-done, indanedione, iV.iV -dimethylbarbituric acid) in the presence of trifluoroacetic acid (substrate activation by protonation) or KOH (activation of the nucleophile) leads to stable cr -adducts 63, whose oxidative aromatization by the action of KMn04 results in 5-substituted 1,2,4-triazine 4-oxides 64 (98MI). 

Wittig reactions of cyclohexanone derivatives in their inclusion compounds with the chiral host 5 gave optically active reaction products. For example, when a mixture of finely powdered 1 1 inclusion compound of 5b with 4-methyl-(15a) or 4-ethylcyclo-hexanone (15b) and phosphorane (16) was kept at 70 °C, the Wittig reaction in the solid state was completed within 4 h. To the reaction mixture was added diethyl ether-petroleum ether (1 1), and then the precipitated triphenylphos-phine oxide was removed by filtration. The crude product left after evaporation of solvent from the filtrate was distilled in vacuo to give (-)-4-methyl- (17a) of 42% ee (73 % yield) or (-)-4-ethyl-l-(carboethoxymethylene)cyclohexane (17b) of 45 % ee (57 % yield), respectively [9], Similar reaction of the 1 1 inclusion compound of 5c and c /. v - 3,5 - dime th y I c y c I o h e x a n o n e (18) with 16 gave 19 of 57 % ee in 58 % yield [9],... 

Amphiphilic resin-supported ruthenium(II) complexes similar to those shown in Structure 3 (cf. also Section 7.5) were employed as recyclable catalysts for dime-thylformamide production from supercritical C02 itself [24], Tertiary phosphines were attached to crosslinked polystyrene-polyethylene glycol) graft copolymers (PS-PEG resin) with an amino groups to form an immobilized chelating phosphine. Catalytic activity declined with each subsequent recycling step, probably due to oxidation of the phosphines and to metal leaching. 

Copper chloride coordinated to aminated polystyrene is active in the oxidation of 2,6-dime thy Iphenol (2,6-DMP) to the DPQ [95]. In the mechanism proposed, a fi-peroxocopper(II) complex of the structure ... 

Experimental verification of the CMD mechanism was pubUshed in 2012 by Ozawa and coworkers, who isolated a single crystal of complex 42 suitable for X-ray analysis and studied the catalytic activity towards C H activation. In solution, this dimeric species disproportionates into two molecules of 43, which is the active catalytic species. They used this species under catalytic conditions to compare the rates of C-H activation of 2-methylthiophene in a competition experiment with half an equivalent of bromobenzene and 2-bromo-l,3-dime-thylbenzene (Scheme 19.7). Oxidative addition, not C H activation, was determined to be the rate-limiting step since coupling with bromobenzene took place preferentially. ... 

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