linolenic+acid

Place syntheses below.

I did some looking around and this is a triunsaturated fatty acid also called an alpha-linolenic acid. Turns out there are many different linolenic acids. Pulling from what we learned in class will we need to use a Pd plate (partially poisened) and alkynes to synthesize the cis double bonds. I think this syn addition will be key. We may also need to utilize Oxymercuration to synthesize the carboxylic acid? not sure on that one.

We will need 18 total carbons and we can't use any starting material greater than 8. A few alkynes with good leaving groups attached, such as Br or Cl, should give us a good start.

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 Rich: I think you are on the right track with the acetylide reactions. You will probably want to start with the middle alkyne and work outwards symmetrically with successive acetylide and NBS bromination to get all alkynes on. I think this will minimize the number of steps. Mercuric acetate will give you a ketone, not an acid. The SIA borane working on a triple bond will give you an aldehyde, which can be converted into an acid. You can also use a protected alcohol (see my comments to Quynh on the pentacosadiynoic acid I think these molecules have a lot in common . Bruce Bondurant

This was the process I thought would work to get Alpha- Linolenic Acid

I think this product would yield a conjugated alkene, not linolenic acid, which ass sp3 carbons between the double bonds. Whereas the conjugated alkene tends to polymerize, the natural procuct is a potent radical inhibitor. Bruce Bondurant


 * NEW CONJUGATED LINOLENIC ACIDS AND METHODS FOR COMMERCIAL PREPARATION AND PURIFICATION -**

New conjugated linolenic acids and methods for commercial preparation and purification - http://www.sumobrain.com/patents/wipo/New-conjugated-linolenic-acids-methods/WO2004013078.html

Wade 6th ed.

Dr. Bondurant, Here is my summary of the synthesis reaction for linolenic acid. Below it are PDF files for the synthesis and retrosynthesis reactions. -Chris Markham Wiki-Synthesis Extra credit For the first reaction I added acetylene to 1,4-bromo-2-butyne with sodium amide. This gave me 6-bromo-1,4-hexyne. I then took the 6-bromo-1,4-hexyne and added butyne with the help of more sodium amide. Separately I added DHP to 8-bromo-octanol with the help of TsOH, to help protect the alcohol group in the next reactions. I then combined the 8-bromo-octanol with the help of TsOH with my other manufactured compound of 1,4,7-decyne using more sodium amide. I subjected this product to a Lindlars catalyst to reduce the triple bonds in a syn fashion to double bonds. Next I took this product and added TFA to remove the THP group, leaving the alcohol open. My last step was to take the product and add Jones Reagent under very cold conditions to turn the alcohol group into a carboxyl group. The product of all these steps is Linolenic acid. Works Cited. L.G. Wade Jr. __Organic Chemistry__ 7th edition. Wikipedia. http://en.wikipedia.org/wiki/Jones_reagent