Effect of Cu(I) on Cyclic Enone Photodimerizations

Article abstract of DOI:10.1021/jo00225a002

Cu(I) can complex with either a nonbonded electron pair on oxygen or with the C=C ? bond in enones and might act as a template to arrange the 2:1 enone-copper complex into the preferred head-to-head regiochemistry.Upon excitation of either the n,?^* or ?,?^* band of the resulting metal complexes of cyclopentenone or of isophorone, however, the proportion of head-to-tail regioisomer observed inthe dimeric products increases.This shift in isomer distribution is caused by metal quenching of the preferentially formed head-to-head 2:1 enone-metal complex