Dearomative Cyclization of Ynamides toward the Formation of Fused Diazabicycles

We report a selective dearomative cyclization strategy for the synthesis of 3,4-fused diazabicycles from 3-substituted pyridyl ynamides. The method combines a chemo-, regio-, and stereoselective carbometalation with a regioselective dearomatization, enabling access to a broad range of diazabicyclic scaffolds with varied ring sizes. The protocol accommodates alkyl and aryl Grignard reagents, tolerates diverse functional groups, and supports stereodivergent synthesis, offering a versatile platform for constructing complex fused N-heterocycles with potential relevance to medicinal chemistry.