reaction of diester and hydroxylamine

[wwbt]

Dear all,

I would like to do the synthetic of hydroxamic acid starting from diester and hydroxylamine. The purpose is to mono-functionalise the -COOEt group and to form the -CO-NH-OH group.

However the problem is that most of the product is di-functionalised compound (even though the less amount of hydroxyl amine has been used).

Do you guys have any suggestion in this case?

Thanks so much!

P.S. The conditions of this kind of reaction are room temperature, stirring, methanol as solvent, and pH > 10.

 

[disc1]

That's an alpha beta di-carbonyl. Those carbonyl carbons are extremely reactive. And if I am not mistaken, the NH-OH group on one will increase the reactivity of the other since NH-OH is very electron withdrawing. So the reaction at one end is pushing the reaction at the other end and the di-substituted molecule is favored.

You might try making the amide first and then hydroxylating. I'm not thinking of a protecting group that you could do on just one end right off the top of my head. Not anything that wouldn't kill the reactivity at the other carbonyl anyway.

How does this relate to aquariums?

 

[reefgeezer]

That's an alpha beta di-carbonyl... How does this relate to aquariums?

Better question: What language is it written in? :lol2:

 

[disc1]

better question: What language is it written in? :lol2:

I was smoking crack anyway, it's a 1-3 dicarbonyl not alpha beta.

 

[disc1]

Lol. Convince me this isn't a homework problem and I'll help you with your synthesis.

 

[JamesJR]

I looked this compound up on the CAS registry and in looking at a bunch of similar compounds I found a reference where they exchanged one of the ethyl esters for a methyl ester. If you could make the conditions mild enough I bet you could easily make this compound with a mixed ester and hydroxylamine. that would be my first guess to try.

 

[wwbt]

Lol. Convince me this isn't a homework problem and I'll help you with your synthesis.

How to convince you?

 

[wwbt]

That's an alpha beta di-carbonyl. Those carbonyl carbons are extremely reactive. And if I am not mistaken, the NH-OH group on one will increase the reactivity of the other since NH-OH is very electron withdrawing. So the reaction at one end is pushing the reaction at the other end and the di-substituted molecule is favored.

You might try making the amide first and then hydroxylating. I'm not thinking of a protecting group that you could do on just one end right off the top of my head. Not anything that wouldn't kill the reactivity at the other carbonyl anyway.

How does this relate to aquariums?

I know that when the first NH-OH is formed the other COOEt will be more reactive than the original one.

Do you have any ideas to change the reactivity of these two ester groups to let this reaction make sense?

 

[disc1]

How to convince you?

How does this relate to aquariums?

 

[wwbt]

I looked this compound up on the CAS registry and in looking at a bunch of similar compounds I found a reference where they exchanged one of the ethyl esters for a methyl ester. If you could make the conditions mild enough I bet you could easily make this compound with a mixed ester and hydroxylamine. that would be my first guess to try.

I also thought about changing one ethyl ester group into a bulky group like t-butyl but this kind of mixed ester may not be commercial available.

With ethyl methyl diester, of course the reactivity will be changed, but not much to let the reaction become more selective (I just guess ^^).

 

[wwbt]

You meant how to control pH value in methanol solvent, right?

I followed the same procedure done with mono ester with NH2OH. It's different in my case (diester) and of course I failed.

 

[disc1]

Maybe this isn't homework...... I just realized the direction that synthesis is going.

You're not trying to make an alpha substituted tryptamine are you?

 

[JamesJR]

Maybe this isn't homework...... I just realized the direction that synthesis is going.

You're not trying to make an alpha substituted tryptamine are you?

Ha I didn't catch this. If somebody wanted to make tryptamines in this manner it sure seems like it is reinventing the wheel doesn't it?

 

[disc1]

What are you trying to make????

 

[bertoni]

This doesn't seem to be reef-related.