Unlocking\nPhotocycloaddition Reactivity of Tropolone\nby Cage-Confined Visible-Light Photocatalysis for Multilevel Selective\nTransformation

The\nprecise asymmetric photochemical transformation of organic\ncompounds containing multiple reactive sites presents significant\nprogress in synthetic chemistry. Herein, we report an unprecedented\nvisible-light-induced cascade transformation of tropolone cyclic triene\nderivatives by using chiral photoactive metal–organic cages\n(cPMOCs) as enzyme-mimicking multipocket photocatalysts. The cage-confined\nphotocatalysis promotes three successive elementary steps, <i>i.e</i>., enantioselective [2 + 2] photocycloaddition with chalcone,\nregio-, and diastereoselective α-ketol rearrangement, and a\nstereoselective 1,3-acyl shift, resulting in bicyclo[3.2.2]nonane\nskeleton with multichiral-centers unattainable by other methods. This\nstudy demonstrates how complex synthetic challenges of peri-, chemo-,\nand stereoselectivities could be subtly manipulated by cage-confined\nsupramolecular catalysis for exploration of new reactivities.