Ru(II)-Catalyzed C-H Functionalization of N-Hydroxyoximes with 1,3-Diynes Unveils a Regioselective Disparity

A highly selective and convenient Ru(II)-catalyzed C-H bond activation protocol has been demonstrated to access 4-alkynylated isoquinolines, which was so far elusive from 1,3-diynes. Subsequently, the same protocol was extended to furnish various 4-4'-biisoquinoline motifs. The key feature of this work is the regioselective disparity observed during the migratory insertion of an organo-ruthenium metallacycle with the C3-C4 triple bond of 1,3-diynes resulting in divergent products as compared to the existing literature.