Photocatalytic synthesis of tetra-substituted furans promoted by carbon dioxide.

We report a simple protocol for the transition metal-free, visible-light-driven conversion of 1,3-diketones to tetra-substituted furan skeleton compounds in carbon dioxide (CO 2 ) atmosphere under mild conditions. It was found that CO 2 could be incorporated at the diketone enolic OH position, which was key to enabling the cleavage of a C-O bond during the rearrangement of a cyclopropane intermediate. This method allows for the same-pot construction of two isomers of the high-value tetra-substituted furan scaffold. The synthetic scope and preliminary mechanistic investigations are presented.