[cvstech]

I have been unable to find a process in forming pent-1-en-2-ol from a carboxylic acid. Any tips on where to start?

[tmartin]

Do you need the enol itself unprotected?  I'm not sure how isoluble that compound would be, it seems to me it could tautomerize back to the ketone.  Maybe you could start from the ketone and trap the enolate as a silyl enol ether?

[cvstech]

I know it well resonate back between the ketone and enol. I am sorry I did not specify that it would be from pentanoic acid. I have been trying to find a way to produce pentyne as an intermediate. Then using that to produce the enol. I do not know if that is the easiest way or not.

[orgopete]

At first, I thought this was an error in naming the product. If not, then the notion that the enol is desired, but acknowledging that it would tautomerize to the ketone, leaves me to wonder, "What is the real question?" Do you mean, "How can one convert pentanoic acid to 2-pentanone?" If so, why would you wish to do so or to repeat myself, what is the real question?

[cvstech]

It is a homework question that reads asks starting with pentanoic acid outline a synthesis for pent-1-en-2-ol. The only way I know of this exsisting is in the tautomeric form made from the addition of water to a alkyne. I am just unable to find a reasonable way to form the pentyne from pentanoic acid.

[tmartin]

It seems to me it would be easier to make the alkyne from the aldehyde (but then you'd have one too many carbons), because there are a few reactions to do just that.  Going from the acid to the alkyne seems pretty "step-y" to me, and not really very easy. 

Can you scan in the exact problem and post it?

[orgopete]

With the clarification that this is a homework type of problem, I would ask the instructor. Speaking from my own experience, I sometimes made errors in writing problems. Asking for the enol certainly strikes me as an instance.

Since this is a student type of problem, let me suggest reactions that may have been discussed in your class.

1) LiAlH4 reduction to 1-pentanol
2) PBr3 or HBr to 1-bromopentane
3) KOtBu to 1-pentene
4) Br2 to 1,2-dibromopentane
5) KOtBu or R2NLi or Na base to 1-pentyne
6) HgSO4/H2SO4/H2O to 2-pentanone