Fig. 4: Mechanistic proposal of the title reaction.
From: Intermolecular 2+2 imine-olefin photocycloadditions enabled by Cu(I)-alkene MLCT
The proposed 2 + 2 IOPC mechanism commences with olefin substrate coordination to TpCu. Ligand exchange experiments indicate that imine substrates undergo rapid and reversible coordination to TpCu. The active TpCu-olefin chromophore then undergoes a MLCT from computationally visualized TpCu-NB HOMO-1 which is primarily Cu-based to TpCu-NB LUMO which is olefin(π*)-based. Capture by the imine C = N double bond leads to azetidine formation and release of TpCu.
