A Stepwise Annulation for the Transformation of Cyclic Ketones to Fused 6 and 7-Membered Cyclic Enimines and Enones

The efficient construction of functionalized polycyclic structures is an important objective in organic synthesis. Herein, we disclose a three-step [2 + n] annulation method for the transformation of cyclic ketones to fused enimines and enones. The method relies on the Suzuki coupling reaction and the amide reductive alkenylation reaction. A series of fused bicyclic (6/6, 6/7, 8/7) and tricyclic (6/6/6; 6/6/7, 6/5/7) ring systems bearing an alpha,beta-enimine or an alpha,beta-enone functionality have been synthetized in good overall yields.