Total Syntheses of Secalonic Acids A and D

Total syntheses of the dimeric tetrahydroxanthone natural products secalonic acids A and D are described. Key steps involve kinetic resolution of the tetrahydroxanthone core structure using homobenzotetramisole catalysis and late‐stage copper(I)‐mediated homodimerization of complex aryl stannane monomers. It takes two: Concise syntheses of the natural products secalonic acids A and D using copper(I)‐mediated dimerization of complex aryl stannane monomers to construct the requisite 2,2′‐biphenol linkage are reported. Highly efficient kinetic resolution of the monomeric tetrahydroxanthone core structures was achieved using homobenzotetramisole catalysis. DMA=N,N‐dimethyl acetamide, MOM=methoxymethyl.