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Addition regioselective acylation

In addition, regioselective enzymatic acylation of pyrimidine 3, 5 -diaminonu-deoside derivatives is possible depending on the biocatalyst employed in the process [28]. N-5 -Acylated products were obtained using CALB as a biocatalyst, whereas PSLC was selective towards the N-3 position. Molecular modeling studies... [Pg.142]

Regioselective acylation of 49a was accomplished by treatment with N- acyl imidazole in the presence of CsF to give 3-0-acyl products 54 in good yields along with a small amount of 3,6-diacyl derivatives (Scheme 3-3). When benzoyl chloride was used, the 6-acyl product was formed to some extent in addition to two products. Interestingly employment of benzoic anhydride showed the opposite tendency giving the 6-benzoate as the main product.3 ... [Pg.404]

Sodium or potassium phenoxide can be carboxylated regioselectively in the para position in high yield by treatment with sodium or potassium carbonate and carbon monoxide. Carbon-14 labeling showed that it is the carbonate carbon that appears in the p-hydroxybenzoic acid product. The CO is converted to sodium or potassium formate. Carbon monoxide has also been used to carboxylate aromatic rings with palladium compoimds as catalysts. In addition, a palladium-catalyzed reaction has been used directly to prepare acyl fluorides ArH —> ArCOF. ... [Pg.718]

A few further general examples of zinc catalytic activity or reactivity include the following. Other zinc-containing systems include a zinc phenoxide/nickel(0) catalytic system that can be used to carry out the chemo- and regioselective cyclotrimerization of monoynes.934 Zinc homoenolates have been used as novel nucleophiles in acylation and addition reactions and shown to have general utility.935,936 Iron/zinc species have been used in the oxidation of hydrocarbons, and the selectivity and conditions examined.362 There are implications for the mechanism of metal-catalyzed iodosylbenzene reactions with olefins from the observation that zinc triflate and a dizinc complex catalyze these reactions.937... [Pg.1231]

The most plausible mechanism proceeds through oxidative addition of the aldehyde to an active Ru(0) species to form (acyl)(hydrido)ruthenium(ll) complex 155. Insertion of the less-substituted double bond of the 1,3-diene into the Ru-H bond occurs to generate an (acyl)( 73-allyl)ruthenmm(ll) intermediate of type 156. Successive regioselective reductive eliminations between the acyl and the 73-allyl ligands provide the desired product with regeneration of the... [Pg.441]

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See also in sourсe #XX -- [ Pg.81 , Pg.86 ]



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Regioselective acylation

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