Asymmetric [5+1] Annulation via C-H Activation/1,4-Rh Migration/Double Bond Shift Using a Transformable Pyridazine Directing Group.

N -Heterocycle-assisted C-H activation/annulation reactions have provided new concepts for the construction and transformation of azacycles. In this work, we disclose a [5+1] annulation reaction using a novel transformable pyridazine directing group (DG). The DG-transformable reaction mode led to the construction of a new heterocyclic ring accompanied by transformation of the original pyridazine directing group via a C-H activation/1,4-Rh migration/double bond shift pathway, affording the skeleton of pyridazino[6,1- b ]quinazolines with a good substrate scope under mild conditions. Diverse fused cyclic compounds can be achieved by derivatization of the product. The asymmetric synthesis of the skeleton was also realized to afford the enantiomeric products with good stereoselectivity.