Hydrogen‐Bonding‐Assisted Cationic Aqua Palladium(II) Complex Enables Highly Efficient Asymmetric Reactions in Water. (16th December 2020) - Kitanosono, Taku
Abstract: Metal‐bound water molecules have recently been recognized as a new facet of soft Lewis acid catalysis. Herein, a chiral palladium aqua complex was constructed that enables carbon–hydrogen bonds of indoles to be functionalized efficiently. We embraced a chiral 2, 2′‐bipyridine as both ligand and hydrogen‐bond donor to configure a robust, yet highly Lewis acidic, chiral aqua complex in water. Whereas the enantioselectivity could not be controlled in organic solvents or under solvent‐free conditions, the use of aqueous environments allowed the σ‐indolylpalladium intermediates to react efficiently in a highly enantioselective manner. This work thus describes a potentially powerful new approach to the transformation of organometallic intermediates in a highly enantioselective manner under mild reaction conditions. Abstract : Metal‐bound water molecules have recently been recognized as a new facet of soft Lewis acid catalysis. A chiral palladium aqua complex was prepared and used to functionalize C−H bonds of indoles in a highly enantioselective manner. The power of the Pd complex was displayed exclusively in water. The inclusion of organic solvents deteriorated the catalysis.