Part I Asymmetric intermolecular Heck reaction of aryl halides Part II Asymmetric addition of organoboroxines to common enones and imines using copper catalysts
Date of Issue2016
School of Physical and Mathematical Sciences
We developed a mild reaction for asymmetric Heck reaction of aryl bromides and chlorides with cyclic olefins. This is the first time that asymmetric intermolecular Heck reactions of aryl halides were realized in high ee. Ammonium salts and alcohol solvent were employed as hydrogen-bonding donors to permit the dissociation of halides from neutral palladium complex, so as to open the door to the enantioselective cationic pathway. We developed a mild reaction for enantioselective conjugate addition of organoboron reagents to acyclic enones. A diverse set of acylic enones bearing alkyl, aryl and heteroaryl groups produced the conjugate adducts in high yields and enantioselectivities. Furthermore, a rare 1,4-insertion pathway through a six-membered cyclic transition state was identified, which was supported by both DFT calculation and natural-abundance C13 KIE experiments. We then successfully applied the reaction system to the enantioselective addition of organoboron reagents to aldimines. The products of chiral amines are important structures in many drugs and drug candidates. The scope of aryl aldimines and arylboroxines were satisfactory and in most cases, >90% ee was obtained.