[Cultivator]

Hello,
I am searching for a reaction that will open a non terminal epoxide on a hydrophobic chain, with a carboxy acid, so that the catalysis will not destroy hydrolyzable parts of the molecule. In a medium, in which no polymerization will likely to occur.

Since acid/Base catalysis is not an option, I am looking for other types of catalysis. There is some little information about metal salen complexes that can work for general epoxide ring opening, but most of them either make a selective opening to OH,OH or other types.

In general, I am looking for some metal complex, so electrophilic, that it will coordinate to the epoxide and strongly polarize one of its carbons, letting the carboxylic acid (or its salt) to attack.

Some things that I found to have a related mechanism of action were Ti(IV) complexes, but they generally require an OH on the nearby position to act selectively. Some Ti(Cp) complexes as well, but all were not very convincing.

What are my options?

[408]

If you are using an electrophilic metal complex are not you not in essence using a lewis acid .  So I assume your compound is only sensitive to protic-type acids?  What type of hydrolyzable groups are present?

[Cultivator]

I did not understand this statement with lewis acid. Anything that accepts electrons is a lewis acid..

Esters, ethers, possibly other sensitive things.

[408]

You mentioned acid catalysis is out of the question, and then you chose to use an electrophillic metal complex, which in essence is a lewis acid.  Why not go with something like an anhydrous metal halide, or even a boron halide, if the boron species is suitable give other functional groups present.

[Cultivator]

Protic acid is acid catalysis. Lewis acid is only an electron pair yanking thing. By the acid catalysis mechanism, the epoxy oxygen gets first protonated (which requires strong acids to be present) - This, I don't want because the same protonation can destroy other bonds in the compound.

One thing I am concerned about metal halides (in case of TiCl4 at least) is that it is being used (with other things) to open epoxides with attaching a Cl to them... (I might be mistaking it for other metal chloride species, but some of them do).

[blind]

BF₃ - Et₂O?

[Cultivator]

Maybe, must check.
If you have other ideas, I am going to check them too. But initially I was searching for metals (or for someone who was experimenting with them) may be I should ask this question in the inorganic forum?

[kiwi]

Have you checked March? In my edition (5th) there is a reference to this sort of thing in section 10-27 (page 490)

[blind]

Why does it have to be a metal?  So long as it does the job, and has no side reactions...

[Cultivator]

It seems like the paper in March's reference doesn't have epoxide at all... (I didn't find).

[kiwi]

It seems like the paper in March's reference doesn't have epoxide at all... (I didn't find).

I only checked one of the references (the Org Syn one) and it certainly does have an epoxide in it. Unfortunately for you the reaction goes via a Pd pi-allyl complex, which I'm assuming is not going to help you. It'd be worth checking out the other Synthesis reference (Otera et. al.) though.

[Cultivator]

Yes, looking back at March's chapter 10 there is much info about epoxides. Didn't see a particular example of making an a-ester b-alcohol, but the chapter is good on other examples.

[orgopete]

How about just posting the problem? I suspect there are solutions, but I really don't know exactly what you are trying to do.