[kmiska]

Hello, i need some help with synthesis or pentan lakton (the picture is here http://hu.wikipedia.org/w/index.php?title=F%C3%A1jl:Delta-valerolactone.png&filetimestamp=20110602165045). I have one reactant Ethyl (2E)-4-hydroxy-2-te butenoat (the picture of structure is here http://www.chemspider.com/ImageView.aspx?id=8782136.

Thank you very much for your advice.

[Dan]

Sow us your ideas first, this is a Forum Rule. We are ethically opposed to doing your homework for you.

[kmiska]

Sow us your ideas first, this is a Forum Rule. We are ethically opposed to doing your homework for you.

It is not my HMW, it is only one part of my synthetic.

[Dan]

You still have to show an attempt. Lactones are cyclic esters, can you think of any general ways to make esters?

[orgopete]

How might you add one carbon and replace the OH?

[kmiska]

How might you add one carbon and replace the OH?

Esters can be prepared from kyrboxyl acid and alcohols (Fishers esterification).

[Dan]

How might you add one carbon and replace the OH?

Oh yeah - I hadn't noticed the extra C.

Esters can be prepared from kyrboxyl acid and alcohols (Fishers esterification).

OK, so how might you make a lactone?

[orgopete]

I think making a lactone may be easy. I think it is more difficult to replace an OH with a carbon or CH2OH. Any ideas?

[Dan]

I think making a lactone may be easy. I think it is more difficult to replace an OH with a carbon or CH2OH. Any ideas?

Me or the OP? I have 3 routes.

I agree that chain extension from the alcohol terminus is more difficult, and quite long winded. That is one strategy I had in mind, but I think a homologation at the ester terminus would be quicker in terms of steps. The quickest option I see is transesterification with a an appropriate alkenol and zip the ring together with RCM.

[orgopete]

Me or the OP?

The original poster. The original poster has not contributed greatly so far, so I mainly ask questions rather than offer advice. If a suggestion were offered, then I might comment upon it.

However, if you think this problem is of such difficulty the original poster may need more help, be my guest. Besides, I am not sure I am seeing your proposed route, other than it being different then mine.

[kmiska]

Me or the OP?

The original poster. The original poster has not contributed greatly so far, so I mainly ask questions rather than offer advice. If a suggestion were offered, then I might comment upon it.

However, if you think this problem is of such difficulty the original poster may need more help, be my guest. Besides, I am not sure I am seeing your proposed route, other than it being different then mine.

How make the dekarboxylation? We leartnt in the school only examples with karboxyl acid.

[bonfire09]

to make a cyclic ester you would need a hexane with two carboxylic groups at each ends. React them with SOCl2 and that will form your lactone because it will react upon itself.

[orgopete]

I was think of converting the OH into a halogen (removing the double bond and reducing the ester) and then displacing the halogen with a one carbon nucleophile that can be easily converted into a carboxylate.