Iridium-catalyzed chemoselective and enantioselective hydrogenation of (1-chloro-1-alkenyl) boronic esters.

Organoboron compounds play important roles in chemistry, especially in the field of organometallic catalysis where boronic acids, boronic esters, and trifluoroborates are invaluable for the construction of C O, C N, or C C bonds through various coupling reactions. a-Amino boronic acids, primarily obtained from (a-chloroalkyl) boronic esters, are a recent addition to this class of compounds, expanding them into completely new areas of use. They are a crucial structural element in a new class of anti-cancer peptide drugs. One member of this class of drugs, which contains a “borleucine” moiety, is marketed under the name bortezomib (Scheme 1).