Pd(II)-Catalyzed Synthesis of Alicyclic[ b ]-Fused Pyridines via C(sp 2 )-H Activation of α,β -Unsaturated N -Acetyl Hydrazones with Vinyl Azides.

A new synthetic protocol for alicyclic[ b ]-fused pyridines with complete regioselectivity from α,β- unsaturated N -acetyl hydrazones and vinyl azides via Pd(II)-catalyzed C-H activation/cyclization/aromatization strategy has been described. A series of five- to eight-membered alicyclic[ b ]-fused pyridines were prepared in a one-step manner with wide substrate scope and good functional group tolerance.