Platinum/Copper Dual-Catalyzed Asymmetric Vinylogous Addition Reactions for the Synthesis of Functionalized Indoles.

Abstract

The development of multicomponent ligands to improve catalytic reactivity and selectivity remains a significant challenge for the synthesis of chiral building blocks. Here, a modular synthesis of structurally diverse multiligated platinum complexes, characterized by X-ray crystallography, was revealed to open up a previously inaccessible reaction space. A library of more than 16 binary component-ligated platinum complexes was identified as a practical toolkit to enable faster screening. The isolated bench-stable Pt(II)(oxazoline)(phosphine) complex paired with a chiral copper complex exhibits fundamentally new cooperative reactivity. The newly designed Pt/Cu dual catalytic system contributed to the development of highly enantioselective vinylogous addition reactions between a Pt-activated electrophilic α,β-unsaturated carbene and a Cu-activated nucleophile, resulting in a reliable process for the asymmetric synthesis of valuable functionalized indoles in good yields and excellent enantioselectivities.