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Topic: Preparation of naphthoic acid ethers - theoretical question  (Read 2949 times)

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Offline Cantacoxinha

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Preparation of naphthoic acid ethers - theoretical question
« on: March 18, 2016, 10:21:03 AM »
I'm running a cpl of reactions where alkylic substituents of various lengths are being attached to the naphthoic acid derivative as shown, thus producing the ethers. Everything works perfectly with simple alkyl substituents, but when it comes to making products with alkene and alkyne substituents, I'm skeptical about the outcome, since the reaction is done with potassium carbonate and is heated, and as far as I know allylic and propargylic units tend to polymerize or get "destroyed" in some other way in contact with base and/or heat. Moreover, after this reaction, a basic hydrolysis of ester moiety is done by boiling in 40% NaOH solution and I'm really afraid whether the products would survive that..

I need an opinion/advice on the outcome of reactions b) and c), is there a prospective for some other base or other way to get these products? (naphthoic acid hydroxy esters must be used as starting materials)

Offline kriggy

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Re: Preparation of naphthoic acid ethers - theoretical question
« Reply #1 on: March 18, 2016, 03:37:18 PM »
You could use TMS protected propargyl bromide and then hydrogenate it to alkene

Offline TheUnassuming

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Re: Preparation of naphthoic acid ethers - theoretical question
« Reply #2 on: March 18, 2016, 04:27:36 PM »
In the ether forming reactions shown will probably work quite well.  Just follow a lit prep for the specifics on equiv. ect and you should be able to get good yields.

The ethers you have shown should be relatively stable to simple saponification conditions, especially if you are careful.  I am surprised you need to boil the substrate in such a large excess of OH to get saponification.  In my experience they usually go much more easily, requiring only room temp and only a slight excess of base if you are worried about side reactions. 
When in doubt, avoid the Stille coupling.

Offline wildfyr

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Re: Preparation of naphthoic acid ethers - theoretical question
« Reply #3 on: March 22, 2016, 11:20:13 PM »
Those reactions should go magnificently. Allyl bromide is an excellent substrate for nucleophilic attack, and propargyl bromide is pretty good too. Hell... I wouldnt even heat these much, and you dont need a phase transfer agent for K2CO3 in DMF, its soluble enough to get things going. And like people said, it doesnt take too much forcing to hydrolyze an ester with KOH, boiling in 40% seems like large overkill.

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