We propose that the mechanism of the electron rich olefin-MVCl2 EDA complex induced oxidative cycloaddition begins with a charge transfer complex formation with the olefin and methyl viologen, followed by visible light irradiation, which initiates single electron transfer generating a radical ion pair. In the presence of oxygen, the radical cation state of methyl viologen is rapidly oxidized back to its di-cation state, effectively suppressing back electron transfer. The formed radical cation 10•+ then undergoes radical cyclization to afford the product radical cation 11•+. This product radical cation can be further oxidized by O2•-or another equivalent of neutral 7, initiating another round of the radical chain reaction and generating the product 9 (Scheme 4).