[marina]

 Hello! 
Cold someone help me with photochemical 2+2 enone cycloadditions or give me some links, where I can found some basic information about this type of reactions, their mechanism and stereochemistry?

[azmanam]

"Enone Olefin [2 + 2] Photochemical Cycloadditions"  Crimmins, M. T.; Renihold, T. L.  Organic Reactions  1993,  44, 297-588.

You'll probably have to go to your library to get it.  Our library doesn't carry the online version of Org. React.

I haven't done them in a while, but I've also done some 2+2 photocycloadditions if you have some basic questions.

[marina]

Thanks on the infromation.   I will see  in the library.
The thing that I don't understnad is why enones react on the carbon and not on the oxygen atom with some alkene?

[azmanam]

you might also try this site:

http://www.cem.msu.edu/~reusch/VirtTxtJml/photchem.htm