A Rational Design of Chiral Iron(III) Complexes for Photocatalytic Asymmetric Radical Cation (4 + 2) Cycloadditions and the Total Synthesis of (+)-Heitziamide A

This work describes the design of chiral iron(III) photoredox catalysis for asymmetric radical cation reactions. The newly developed catalysis successfully minimizes the use of chiral sources and exhibits high tunability, thereby enabling a highly enantioselective (4 + 2) cycloaddition of chalcone derivatives. A mechanistic study revealed the details of the cycloaddition steps that account for the observed stereoselectivity. Furthermore, the unique regioselectivity of the radical cation (4 + 2) cycloaddition enabled us to accomplish the first asymmetric total synthesis of (+)-heitziamide A.