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Cercosporin-Photocatalyzed [4+1]- and [4+2]-Annulations of Azoalkenes Under Mild Conditions
Published on: July 17, 2020
Perylenequinone natural products: total synthesis of hypocrellin A
Erin M O'Brien1, Barbara J Morgan, Carol A Mulrooney
1Department of Chemistry, Roy and Diana Vagelos Laboratories, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA.
Abstract:
An efficient and stereoselective total synthesis of the perylenequinone natural product hypocrellin A (1) is described. The key features include a potentially biomimetic 1,8-diketone aldol cyclization to set the centrochiral C7,C7'-stereochemistry, bis(trifluoroacetoxy)iodobenzene mediated oxygenation, a palladium-catalyzed decarboxylation, and an enantioselective catalytic oxidative 2-naphthol coupling to establish the biaryl axial chirality. The helical stereochemistry is formed from an axial chiral intermediate and is then utilized in a dynamic stereochemical transfer to dictate the stereochemistry of the C7,C7'-seven membered ring formed during the aldol cyclization.
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