Influences of Lewis Acids on the Photochemical Cyclodimerization of Cyclopentenone

Article abstract of DOI:10.1246/bcsj.60.423

In the presence of tin(IV) chloride, photochemical dimerization of cyclopentenone gave a cis-transoid-cis head-to-head dimer as predominant product.Other Lewis acids such as zinc(II) bromide, boron trifluoride etherate, tin(II) chloride, and silver(I) trifluoromethylsulfonate, however showed little influence.Tris(2,2,6,6-tetramethyl-3,5-heptanedionato)lanthanum(III) affected regiochemistry of the reaction in a way to favor a head-to-tail dimer.