Iridium‐Catalyzed Chemoselective and Enantioselective Hydrogenation of (1‐Chloro‐1‐Alkenyl) Boronic Esters

Persistent chlorine: Hydrogenation of borolane-substituted vinylic chlorides catalyzed by IrP N complexes greatly preserved the chlorine substituent on the hydrogenated product, with only 3–19 % of dechlorinated byproducts present after hydrogenation. The α-chloro boronic ester products are ideal precursors for proteasome-inhibitor-type anti-cancer drugs, a fact which demonstrates the utility of this hydrogenation method.