Asymmetric Halocyclizations of Unsaturated Compounds: An Overview and Recent Developments

This review covers the recent advances concerning the elusive enantioselective biomimetic cyclization of functionalized unsaturated compounds promoted by halonium ions. The asymmetric halocyclization of multiple carbon-carbon bonds is an important class of organic reactions as it provides stereodefined carbon-halogen bond-containing compounds, which are ubiquitous in nature and other bioactive molecules. Although the halocyclization reaction is known since long, attempts to carry out this electrophilic cyclization process in an asymmetric way had largely been unsuccessful and the first synthetically useful examples have appeared in the last few years. The most important progresses in this field are summarized.