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I am aware that esters can be selectively hydrolysed depending on the type of alkyl group present e.g. Me ester vs t-butyl ester, the latter is reactive to acidic conditions and not basic because of its inability to form tetrahedral intermediate. But what reagent could I use to carry out the following transformation?

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I see it is the O-C bond that breaks, so it is acyl cleavage (Ac). Acidic conditions would destroy my Me ester as would basic, so how can I get around this? Could a big bulky base, say LDA, take it down a B(Ac)2 route (generate CO2?)

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If you use methanol as a solvent and add a suitable base, you should end up with the correct product, since any MeOH attacking the protecting group you want to keep will simply re-form the methyl ester, whereas the acetate will cleave to give the unprotected alcohol.

You could potentially also achieve this using sodium methoxide/methanol to speed the reaction up, but standard potassium carbonate/methanol is usually just fine.

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  • $\begingroup$ this makes sense as it would reversibly add/leave. how does cleavage take place mechanistically? Is it attack of methanol at the carbonyl then leaving group is the "rest of the ester" $\endgroup$ – gamma1 May 27 '17 at 18:00
  • $\begingroup$ Pretty much. Standard addition elimination mechanism $\endgroup$ – NotEvans. May 27 '17 at 18:17
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You could try refluxing in NaOMe/MeOH. The presence of methanol would preserve the methyl ester, while transesterification would produce methyl acetate as a by-product.

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