[limonade]

Say I have the first compound in the picture and I wanted to react  only the ketone and not the ester, with grignard reagent (not shown)


How does one go about protecting the ester to avoid the reaction with 2 equivalents of grignard  (instead of protecting the ketone through formation of cyclic acetal)?
 

[Dan]

1. Why would you use 2 equiv. of the Grignard reagent?
2. One solution might be to use a less reactive nucleophile (i.e. with better chemoselectivity).
3. Another solution is to use a less reactive carboxylic acid derivative.

Can you think of any possibilities for 2 and 3?

[limonade]

1. Why would you use 2 equiv. of the Grignard reagent?
2. One solution might be to use a less reactive nucleophile (i.e. with better chemoselectivity).
3. Another solution is to use a less reactive carboxylic acid derivative.

Can you think of any possibilities for 2 and 3?

1. Sorry... Only one equivalent.

2. Still thinking

3. Possibly I could do a reverse esterfication to make a carboxylic acid, then convert to amide?

[mjpam]

3. Possibly I could do a reverse esterfication to make a carboxylic acid, then convert to amide?

• The alkoxy oxygen in an ester is already divalent, so it would difficult to protect the ester as an ester
• Esters undergo ammonolysis directly to amides
• The are protecting groups that protect both the cabonyl and hydroxly of a carboxylic acid and are base/nucleophile-resistant: see here

[orgopete]

Say I have the first compound in the picture and I wanted to react  only the ketone and not the ester, with grignard reagent (not shown)

How does one go about protecting the ester to avoid the reaction with 2 equivalents of grignard  (instead of protecting the ketone through formation of cyclic acetal)?

Let's say you wanted to reduce the ketone and not the ester, how might you do that? Couldn't you apply the same strategy for a Grignard reaction?