Abstract
In this account, we describe our journey leading to the discovery of a generally applicable umpolung method for the α-functionalization of ketones. Central to this reaction is the cyclic hypervalent fluoro-iodane, which is mostly known for various alkene functionalizations enabling, for example, the synthesis of fluoro-benzoxazepines, indoles, and ketones. During this work, we encountered α-functionalized ketones as minor side products. This observation prompted us to further investigate this reactivity, thus revealing a directed umpolung of pyridyl ketones by the fluoro-iodane. The key to the success was the unexpected non-covalent interaction between the nucleophile, substrate, and iodane.
1 Introduction
2 Cyclizations Triggered by the Fluorination of Styrenes
3 Umpolung Reactions Facilitated by Hypervalent Iodanes
4 Discovering and Evolving a Fluoro-Iodane-Triggered Regioselective α-Functionalization of Carbonyl Compounds
5 First Investigations on the Nitrogen-Directed Umpolung
6 Conclusion
Key words
hypervalent iodane - fluorination - umpolung of ketones - non-covalent interactions - α-functionalization - halogen bonding