Photochemical dimerization in solution of heterocyclic substituted alkenes bearing an electron withdrawing group

The photochemical dimerization in solution of heterocycle substituted alkenes bearing electron withdrawing groups is reported. The reactions occurred both in the singlet and in the triplet slates showing good regio- and stereoselectivities. The regioselectivity can be explained assuming that the dimerization reaction is frontier orbitals controlled The stereoselectivity can be explained assuming the formation of the most stable isomers.