Benzyl esters electronic effects

Polymer supported methyltriazine, CH2CI2, rt, 34-100% yield. The process is effective for both aromatic and alkyl acids. Ethyl and benzyl esters have also been prepared by this method. Acidic phenols such as 4-nitrophenol can be methylated by this method but more electron-rich phenols give excruciatingly slow reactions. The rate of reaction is pAj,-dependent. 

In the absence of benzylic electronic effect, the ester group on aziridines 172 and 174[75] (jiiected the C—bond cleavage effectively to give j8-amino esters (Scheme 52). 

Benzyl-alkyl, dialkyl, cyclic and acyclic ethers were converted to esters or lactones by RuO or [RuO ] (RuClj/aq. Na(C10) or Ca(C10)j/CH2Cl2). It was not stated whether RuO or [RuO ] was the effective oxidant, but oxidation of jb-methoxy-benzyhnethyl ether apparently involved a one-electron transfer process, which might be more likely to occur with [RuO ] [426],... 

Co2(CO)8-catalyzed reactions of benzylic acetates with trimethylsilane and CO proceed under mild reaction conditions to give trimethylsilylethers of /3-phenethylalcohol in 43-76% yield. The highest yields are observed for benzyl acetates with electron-donating substituents.111 Secondary alkyl acetates are also good substrates in the reaction system, yielding enol silyl ethers.112 In addition, the cobalt complex is an effective catalyst for siloxymethylation of five-membered cyclic ortho esters, as shown in Eq. (41).113... 

From the temperature dependence of the substantial kinetic isotope effect (KIE) observed in the oxidation of diols to hydroxycarbonyl compounds by 2,2/-bipyridinium chlorochromate (BPCC), it is proposed that hydride transfer occurs in a chromate ester intermediate, involving a six-electron Hiickel-type transition state.9 A similar conclusion is drawn for the oxidation of substituted benzyl alcohols by quinolinium chlorochromate.10... 

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