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An oxidative catalytic vanadium(V) system was developed to access the naturally nonabundant diastereomers of carpanone from the corresponding alkenyl phenol monomer in one pot by tandem oxidation, oxidative coupling, and 4+2 cyclization. This system was applied to the synthesis of two other analogues of carpanone. Mild oxidizing silver salts were used as the terminal oxidant to minimize background oxidation which produces the natural diastereomer of carpanone. Further, the first examples of enantioselective oxidative benzoxanthenone formation are reported. Solvent polarity has a strong effect on enantioselectivity, consistent with a mechanism involving binding of vanadium Schiff base catalysts to the alcoholic moiety of the alkenyl phenols during the cyclization step.

A facile method to oxidatively trimerize phenols using a catalytic aerobic copper system is described. The mechanism of this transformation was probed, yielding insight that enabled cross‐coupling trimerizations. With this method, the natural product pyrolaside B was synthesized for the first time. The key strategy used for this novel synthesis is the facile one‐step construction of a spiroketal trimer intermediate, which can be selectively reduced to give the natural product framework without recourse to stepwise Ullmann‐ and Suzuki‐type couplings. As a result, pyrolaside B can be obtained expeditiously in five steps and 16 % overall yield. Three other analogues were synthesized, thus highlighting the utility of the method, which provides new accessibility to this area of chemical space. A novel xanthene was also synthesized through controlled Lewis acid promoted rearrangement of a spiroketal trimer.