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

Summary of main observation and conclusion 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 α,β‐enimine or an α,β‐enone functionality have been synthetized in good overall yields. An expedient protocol for the efficient assembly of cyclic ketones and ω‐unsaturated amides in a “2 + n” manner to produce fused enimines and enones has been developed.