Novel Noncovalent Interactions in Catalysis: A Focus on Halogen, Chalcogen, and Anion-π Bonding

Abstract

Noncovalent interactions play an important role in many biological and chemical processes. Among these, hydrogen bonding is very well studied and is already routinely used in organocatalysis. This Short Review focuses on three other types of promising noncovalent interactions. Halogen bonding, chalcogen bonding, and anion-π bonding have been introduced into organocatalysis in the last few years and could become important alternate modes of activation to hydrogen bonding in the future.1 Introduction2 Halogen Bonding3 Chalcogen Bonding4 Anion-π Bonding5 Conclusions

Chalcogen Bonding Catalysis of a Nitro‐Michael Reaction

“…Non‐covalent organocatalysis has thus far been dominated by hydrogen bonding (HB), with primarily (thio)urea derivatives being used as catalyst backbones . Nonetheless, other weak interactions such as anion–π interactions, halogen bonding (XB), and chalcogen bonding (ChB) have attracted ever‐increasing interest lately, and particularly the first two modes are now also established in organocatalysis . In contrast, the application of ChB donors as intermolecular Lewis acidic catalysts is a hardly explored concept, and first examples were only published in 2017 .…”

Halogen Bonding in Solution: Anion Recognition, Templated Self‐Assembly, and Organocatalysis

“…Taking into account the similarities as well as beneficial differences between HBs and XBs (e.g.higher directionality, potential tuneability), the increasing number of investigations on the potential application of XB donor systems as catalysts (or at least as activators) in organic synthesis was al ogical consequence. [22,24,61] There is an excellent review from the Huber group that provides adetailed overview of the historic development of XBs in organic synthesis as well as asummary of XB-based activators/catalysts up to the beginning of 2016. [22] Thus,t his Minireview only focuses on some highly topical examples from mid-2015 onwards.…”

Mechanisms in Iodine Catalysis

“…Halogen bonds are noncovalent interactions between the electrophilic region of a halogen atom and a Lewis base . Besides applications in crystal engineering, or anion recognition, halogen‐bond‐based catalysts have successfully been employed as organocatalysts ,. Among these catalysts, molecular iodine could be the simplest halogen‐bond donor that displays a catalytic activity.…”