Fine-Tuning Substrate-Catalyst Halogen-Halogen Interactions for Boosting Enantioselectivity in Halogen-Bonding Catalysis

A new approach towards highly enantioselective halogen-bonding catalysis has been developed. To circumvent the intrinsic issues of the nature of the halogen-bond (XB) and the resultant unresolved limitations in asymmetric catalysis, fine-tuned halogen-halogen interactions between the substrate and XB-donor were designed to preorganize the substrate in the catalyst's cavity and boost enantiocontrol. The present strategy exploits both the electron cloud (Lewis base site) and the sigma (& sigma;)-hole site of the halogen substituent of the substrates to form a tight catalyst-substrate-counteranion chiral complex, thus enabling a controlled induction of high levels of chirality transfer. Remarkable enantioselectivities of up to 95 : 5 e.r. (90 % ee) have been achieved in a model dearomatization reaction of halogen-substituted (iso)quinolines with tetrakis-iodotriazole multidentate anion-binding catalysts.

Automated summary

A new approach to achieve highly enantioselective halogen-bonding catalysis has been developed by designing fine-tuned halogen-halogen interactions. This strategy utilizes both the electron cloud and sigma-hole site of the substrate's halogen substituent to form a tight chiral complex, enabling controlled induction of high levels of chirality transfer. Remarkable enantioselectivities of up to 95:5 e.r. (90% ee) have been achieved in a model dearomatization reaction using tetrakis-iodotriazole multidentate anion-binding catalysts.