Oxygen-carbon bonds reactions with

An analogous reaction occurred with oxiranes which underwent mainly carbon-oxygen bond cleavage, with formation of a-hydroxyketones. In some instances byproducts arising from carbon-carbon bond cleavage were also formed in triphenyl-oxirane this mode dominated and the sole product was the hydroxyketone Ph2C(OH)COPh (80%) [54],... 

Carbon-oxygen bonds are formed by the Ullmann reaction (- coupling of aryl halides with copper) which has been varied in alkaloid chemistry to produce diaryl ethers instead of biaryls. This is achieved by the use of CuO in basic media (T. Kametani, 1969 R.W. Dos-kotch, 1971). 

Just as the carbon-oxygen bond of alcohols is cleaved on reaction with hydrogen halides (Section 4 8) so too is an ether linkage broken... 

Benzyl and alkyl tnalkylsilyl ethers undergo clean fluonnation to give good yields of benzyl and alkyl fluorides, respectively, when reacted with a combination of d quaternary ammonium fluoride and methanesulfonyl orp- toluenesulfonyl fluoride. The reactions are applicable strictly to a primary carbon-oxygen bond, secondary and tertiary alkyl silyl ethers remain intact or, under forcing conditions, aie dehydrated to olefins [29] (equation 22)... 

Hydrogenation of epoxides lends itself well to both synthetic applications and mechanistic studies. The reaction is complex, for either carbon-oxygen bond may break with or without inversion of configuration, and the product may contain deoxygenated products (92,93) as well as ketones derived by isomerization (26). The reaction is especially sensitive to both catalyst and environment (74). 

Hydrolysis is one of a family of reactions which leads to the transformation of pollutants. Under environmental conditions, hydrolysis occurs mainly with organic compounds. Hydrolysis is a chemical transformation process in which an organic RX reacts with water, forming a new molecule. This process normally involves the formation of a new carbon-oxygen bond and the clearing of the carbon-X bond in the original molecule ... 

The asymmetric Darzens condensation, which involves both carbon-carbon and carbon-oxygen bond constructions, was realized by use of the chiral azacrown ether 75als2,s ,ss and the quaternary ammonium salts derived from cinchona alka-loids159"621 under phase transfer catalyzed conditions. The a,p-epoxy ketone 80 (R=Ph) was obtained with reasonable enantioselectivity by the reaction of... 

In this reaction, only the benzylic carbonate can react readily since cleavage of the benzylic carbon-oxygen bond leads to a stabilized carbocation while no such stabilization would exist for the hypothetical products which would be obtained by cleavage of the phenyl carbonate. The benzylic carbocation intermediate which is formed can either eliminate to the corresponding styrene 4 or recombine with the nucleophilic methanol which is formed by decarboxylation. It is the latter reaction which appears to prevail at room temperature as the ether 2 can be isolated in excellent yield. Subsequent heating in the presence of acid catalyst drives the reaction to the elimination product 6 and free methanol. 

On the other hand, in cyclic ethers (alkene oxides, oxetans, tetrahydrofuran) and formals the reaction site is a carbon-oxygen bond, the oxygen atom is the most basic point, and, hence, cationic polymerization is possible. The same considerations apply to the polymerization of lactones Cherdron, Ohse and Korte showed that with very pure monomers polyesters of high molecular weight could be obtained with various cationic catalysts and syncatalysts, and proposed a very reasonable mechanism involving acyl fission of the ring [89]. 

The authors concluded that the transition states for the Menshutkin reactions of the benzyl substrates were early (reactant-like) with nitrogen-alpha carbon bond formation lagging behind alpha carbon-oxygen bond rupture. The transition states for the Menshutkin reactions with the methyl and ethyl substrates, on the other hand, are tight (product-like) with nitrogen-alpha carbon bond formation greater than alpha carbon-oxygen bond rupture. 

Oxidative addition involving carbon-to-oxygen bonds is of relevance to the catalysis with palladium complexes. The most reactive carbon-oxygen bond is that between allylic fragments and carboxylates. The reaction starts with a palladium zero complex and the product is a ir-allylic palladium(II) carboxylate Figure 2.16. 

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