Rh(III)-Catalyzed Dual C–H Functionalization/Cyclization Cascade by a Removable Directing Group: A Method for Synthesis of Polycyclic Fused Pyrano[<i>de</i>]Isochromenes

An interesting Rh­(III)-catalyzed dual C–H functionalization/cyclization cascade of azomethine imine with diazophosphonate by a removable directing group for the synthesis of highly fused pyrano­[de]­isochromene has been achieved. The transformation shows that the desired pyrano­[de]­isochromenes with two oxygen atoms on its core scaffold could be constructed with good to excellent yields (up to 86%) via a facile one-pot, multiple-step cascade reaction, along with broad generality and versatility.