Redox-Neutral Propargylic C-H Functionalization by Using Iron Catalysis

In spite of their rich stoichiometric chemistry, cyclopentadienyliron(II) dicarbonyl complexes are rarely used as catalysts in organic synthesis. Inspired by precedents in the chemistry of cationic olefin complexes and neutral allylmetal species, our group has developed a coupling of alkynes or alkenes with aldehydes and other carbonyl electrophiles to give homopropargylic and homoallylic alcohols, respectively, by using a substituted cyclopentadienyliron(II) dicarbonyl complex as the catalyst. In this article, we first contextualize this development within the conceptual background of C-H functionalization chemistry and relative to key stoichiometric precedents. We then give an account of our group's discovery and development of the catalytic alpha-functionalization of alkenes and alkynes with electrophilic reagents. Introduction Preliminary Stoichiometric Work Hydroxyalkylation Development and Scope Conclusions and Future Directions