[HaroTaro]

I'm always having problem starting this kind of questions: Provide reagents and write out steps for th efollowing multi-step synthetic transformation. Please see if I'm doing this correctly.
For this question, I know that we have to conver the alkyne to alkane first and we can't deprotonate an alkane. So...
1. deprotonate alkyne with LDA
2. Add H2
3. add H+ and water to deprotonate the alcohol so that we end up with CH3COO-

The problem I encountered now is that after step 1and 2, one carbon would have a negative charge. After step3, alcohol would have a negative charge. So how does that work? What am I doing wrong?

[macman104]

You can't deprotonate and then reduce the alkyne.  If you want to deprotonate, you need to do something with it.  Also, it is going to deprotonate at the terminal end of the alkyne.  Also, the oxygen species is not a good nucleophile

I would suggest something like this.

1)  Reduce to alkene
2)  Hydroxymercuration-Demercuration to give the secondary alcohol
3)  Conversion of the acid to an acid chloride or ester
4)  Deprotonate alcohol and have it attack ester

[HaroTaro]

Thanks for replying~

How about this...

Turn alkyne ot alkene
then use H from the alcohol to protonate alkene (alcohol just dissociate in water right??? so no specific reagent needed?)
The alkene would then turn into a alkyl group and joined with the carboxyl group?
  I'm very suspicious of my own work...

[oc dummy]

I am having trouble approaching the question too. What does it mean by "steps for multi-step synthetic transformation but not the mechanistic steps"?

I do not know where to start because theres already the CH3COOH there..

[oc dummy]

I think first, you add Lindlar catalyst to get the alkene...
then add H+, H2O so you get an alcohol in which the O will attact the carbonly center of the carboxylic acid....

[macman104]

You first need to activate your carboxylic acid to being attacked by the alcohol oxygen.  Right now, it won't work because the OH of the carboxylic acid is not a good leaving group.  You either need to make it an acid chloride or an ester.

[oc dummy]

here is what I have.

1. SOCl2 making the carboxylic acid with Cl
2. Lindlar's catalyst, chaging the alkyne to alkene
3. H+, H2O to change the alkene into alcohol
4. H2SO4, acid catalyst for the reaction of the alcohol attacking the acyl chloride.

Is this correct?

[macman104]

Essentially what I proposed in my first post...but yes, that looks like a valid pathway.

[Two00proof]

Am I the only one that noticed that you lose a carbon?  Is that correct, or is that a typo?

[macman104]

Am I the only one that noticed that you lose a carbon?  Is that correct, or is that a typo?

You're the only one to see that, because you don't lose a carbon.  6 carbons on the left, 6 on the right...

[kiwi]

here is what I have.

1. SOCl2 making the carboxylic acid with Cl
2. Lindlar's catalyst, chaging the alkyne to alkene
3. H+, H2O to change the alkene into alcohol
4. H2SO4, acid catalyst for the reaction of the alcohol attacking the acyl chloride.

Is this correct?

bear in mind you can add a carboxylic acid directly across an alkene to give the Markivnikov addition product, using a touch of a catalyst like Pd, Hg or Th