Synthesis of α-Dunnione Analogues with Cytotoxicity against HepG2 Cells via Hydrogen Atom Transfer Strategy

α-Dunnione analogues are regarded as promising candidates for anticancer drug development, while their synthetic methods remain limited. Herein, an efficient Fe(III)-catalyzed hydrogen atom transfer (HAT) strategy is developed for construction of a series of α-dunnione analogues. In this approach, iminophosphorane promotes a reductive radical alkylation to form a quinoid species intermediate, which subsequently undergoes Fe-catalyzed reductive cleavage of the N-P bond and intramolecular cyclization. Among the synthesized derivatives, compounds 3a, 3d, 3e, 3g and α-dunnione exhibits pronounced cytotoxic activity against HepG2 cells. Overall, this study provides an efficient synthetic route to biologically active α-dunnione analogues.