Cobalt-Catalyzed Selective Hydroboration/Cyclization of 1,6-Diynes.

Disclosed herein is a cobalt-catalyzed chemo-, regio-, and stereoselective hydroboration/cyclization of 1,6-diynes. Using a commercially available bisphosphine ligand (dppp), this mild protocol accommodates 1,6-diynes bearing one internal alkyne, two internal alkynes, or two terminal alkynes, furnishing boryl-containing 1,2-dialkylidenecyclopentanes in moderate to good yields. Synthetic applications and preliminary bioactivity screening against HepG2 cells were performed to demonstrate the practicality of this method. Moreover, mechanistic experiments suggest a catalytic cycle involving a Co(I)-H species.