Exchange reactions ethers

Exchange Reactions of Alkenyl Ethers and Esters Catalyzed by Pd(II)... 

The key step in the total synthesis of rhizobitoxine is the Pd-catalyzed exchange reaction of the methyl alkenyl ether moiety in 4 with the functionalized alcohol, although the yield is low[3]. The enol pyruvate 6 (a-ethoxyacrylic acid) is prepared by the reaction of methyl a-methoxyacrylate or a-methoxy-acrylic acid (5) with ethanol catalyzed by PdCl2(PhCN)2 at room temperature in the presence of CuCli and NaH2P04[4],... 

Liquid coating resins are prepared by reacting methanol or butanol with the initial hydroxyme-thylureas. Ether exchange reactions between the amino resin and the reactive sites on the polymer produce a cross-linked film. 

The 2+2 cycloadditions of benzyne to cis- and trani-propenyl ether gave cis- and fran -benzocyclobntanes as the main products, respectively [ 117,118], Stereospecific [2+2] cycloaddition reactions were observed between the benzyne species generated by the halogen-Uthium exchange reaction of ort/io-haloaryl triflates and the ketene silyl acetals (Scheme 23) [119],... 

Bonner, using the isotopic method ( Sb) and either precipitation of the oxinate of Sb(III) or an isopropyl ether extraction of Sb(V), obtained the first results on this exchange reaction. In media 6 M HCl a complex rate law, viz. 

Baker et al, have obtained some kinetic data on the exchange reactions between the 1,10-phenanthroline, 2,2 -dipyridine and 2,2, 2"-tripyridine complexes of Co(III) and Co(ll) in both H2O and D2O solution. The isotopic method ( Co) and separations involving either extraction of Co(II) with organic solvents (n-hexanol-ether or saturated sodium acetate in n-hexanol) or precipitation of Co(III) as Co(phen)3(l3)3 were used. For the 1,10-phenanthroline system, a rate law... 

The reaction in Entry 8 was conducted in excess refluxing vinyl f-butyl ether, using 1.1 equivalent of Hg(OAc)2 to catalyze the exchange reaction. In Entry 9 a thermal reaction leads to formation of an eight-membered ring. 

Methoxymethylation of alcohols is generally achieved through alkylation with chloromethyl methyl ether. The procedure described here for the preparation of Bu3SnCH20CH20CH3 avoids the use of the highly toxic chloromethyl ether by employing an acid-catalyzed acetal exchange reaction with dimethoxymethane for the... 

As known, compounds of the (R3Sn)2X type enter readily into various exchange reactions.62 No intermediate silicon organophosphorus betaine 61 with the oxide anionic center was detected in the reactions of thiobetaines 20a, with (R3Sn)20 in ether at room temperature.84,96,100 In solutions they... 

Vardanyan [65,66] discovered the phenomenon of CL in the reaction of peroxyl radicals with the aminyl radical. In the process of liquid-phase oxidation, CL results from the disproportionation reactions of primary and secondary peroxyl radicals, giving rise to trip-let-excited carbonyl compounds (see Chapter 2). The addition of an inhibitor reduces the concentration of peroxyl radicals and, hence, the rate of R02 disproportionation and the intensity of CL. As the inhibitor is consumed in the oxidized hydrocarbon the initial level of CL is recovered. On the other hand, the addition of primary and secondary aromatic amines to chlorobenzene containing some amounts of alcohols, esters, ethers, or water enhances the CL by 1.5 to 7 times [66]. This effect is probably due to the reaction of peroxyl radicals with the aminyl radical, since the addition of phenol to the reaction mixture under these conditions must extinguish CL. Indeed, the fast exchange reaction... 

Judging from these findings, the mechanism of Lewis acid catalysis in water (for example, aldol reactions of aldehydes with silyl enol ethers) can be assumed to be as follows. When metal compounds are added to water, the metals dissodate and hydration occurs immediatdy. At this stage, the intramolecular and intermolecular exchange reactions of water molecules frequently occur. If an aldehyde exists in the system, there is a chance that it will coordinate to the metal cations instead of the water molecules and the aldehyde is then activated. A silyl enol ether attacks this adivated aldehyde to produce the aldol adduct. According to this mechanism, it is expected that many Lewis acid-catalyzed reactions should be successful in aqueous solutions. Although the precise activity as Lewis acids in aqueous media cannot be predicted quantitatively... 

We distinguished between alcohols and ethers and between thiols and thioethers, and so we will consider the three relevant exchange quantities for amines, one apiece for primary, secondary and tertiary species. For each exchange reaction, all species are in the... 

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