Regio- and Enantioselective Allylic Alkylation of Terminal Alkynes by Synergistic Rh/Cu Catalysis
Changkun Li describes the Rh/Cu-catalyzed regio- and enantioselective synthesis of 1,4-enynes.
1,4-Enynes are important building blocks in organic synthesis, as they are endowed with a versatile combination of reactive double and triple bonds. Transition-metal-catalyzed asymmetric allylic substitutions represent the main method for accessing chiral 1,4-enynes in an enantioselective manner. Professor Changkun Li from the Shanghai Jiao Tong University (P. R. of China) explained that alkynyl-aluminum/boron compounds and alkynyl carboxylic acids were successfully used in the synthesis of 1,4-enynes. However, from the viewpoint of atom- and step-economy, direct asymmetric allylation of easily available terminal alkynes is attractive but challenging. Therefore, a new catalyst system that controls both the regio- and the enantioselectivities in the coupling of general terminal alkynes and unsymmetrical allylic precursors is still in high demand.