Stereoselective Chromium‐Catalyzed Semi‐Hydrogenation of Alkynes

Abstract

Abstract Chromium complexes have found very little applications as hydrogenation catalysts. Here, we report a Cr‐catalyzed semi‐hydrogenation of internal alkynes to the corresponding Z ‐alkenes with good stereocontrol (up to 99/1 for dialkyl alkynes). The catalyst comprises the commercial reagents chromium(III) acetylacetonate, Cr(acac) 3 , and diisobutylaluminium hydride, DIBAL−H, in THF. The semi‐hydrogenation operates at mild conditions (1‐5 bar H 2 , 30 °C).