ReI-Catalyzed highly regio- and stereoselective C–H addition to terminal and internal alkynes

We have developed an effective ortho C–H functionalization of arylpyridines and detachable N-pyrimidyl indoles by terminal and internal alkynes using a Re(I) catalyst providing an efficient access to various E-selective alkenylation products. The catalytic reaction is compatible with various aliphatic alkynes, aromatic terminal alkynes and internal alkynes, and structurally different nitrogen heterocycles. Deuterium-labeling experiments indicate that significant deuterium scrambling occurs with the directing groups and acetylenic sp C–H bonds before the migratory insertion.