[quantumnumber]

Hi guys,
I was wondering if using MCPBA with an enone (propenal, for example) would produce the epoxide, oxidazing as usual the double bond; or if the reactivity of this double bond changes because of the conjugation with the C=O bond, giving as a result a different product

What do you think?

[orgopete]

I would say in general, MCPBA is an electrophile and the most electron rich alkenes react at the fastest rate. In this case, the alkene is deactivated and the reaction will be retarded and I think will not react as an isolate alkene would. Epoxides of unsaturated ketones can be made by conjugate addition and elimination with basic hydrogen peroxide. Can basic MCPBA do the equivalent reaction? The problem with this is you have a very reactive aldehyde. They are also easily oxidized. A Bayer-Villiger type of reaction on an aldehyde will give an acid.

The target molecule seems simple and likely to be present in the literature. Why not just look up how it has been made?

[quantumnumber]

I would say in general, MCPBA is an electrophile and the most electron rich alkenes react at the fastest rate. In this case, the alkene is deactivated and the reaction will be retarded and I think will not react as an isolate alkene would. Epoxides of unsaturated ketones can be made by conjugate addition and elimination with basic hydrogen peroxide. Can basic MCPBA do the equivalent reaction? The problem with this is you have a very reactive aldehyde. They are also easily oxidized. A Bayer-Villiger type of reaction on an aldehyde will give an acid.

The target molecule seems simple and likely to be present in the literature. Why not just look up how it has been made?

I agree in everything you said. In order to avoid Baeyer-Villiger, the alkene could be oxidized with MCPBA protecting the keto group first as a thioacetal (this also avoid electronic delocalozation).

By the way, could you explain the method you mentioned to make epoxides from enones? I think i don't know it. Thanks a lot!

[orgopete]

MCPBA will also oxidize the sulfuric. Can you look up a literature reference to the target compound. Let's start there.

[zsinger]

Yes, it does.  I know this for a fact, as one of the kids in my research teams researches particularly this.  It also has many stereochemical consequences (some good, some bad…), believe it or not.  We use organo-catylsts to get around those enantio-selectivity problems!  Gotta be very careful about how reactive the nucleophile is, as one which is too reactive will surely react in the 1-2 manner.
      -Zack