Abstract
The first total syntheses of oresbiusin A in the (+)-, (-)-, and (±)-forms were accomplished in five steps with overall yields of ca. 70 %. The key intermediates with optical activity were generated through a Sharpless asymmetric dihydroxylation reaction. These efforts allowed us to establish the absolute configuration of this natural product with dextrorotary and a 2S configuration. In addition, the total syntheses of both enantiomers of oresbiusin B along with its racemate were accomplished in six steps with overall yields of 58 %. Among these compounds, the unnatural oresbiusin A with a levorotary rotation was found to possess dose dependent anti-HIV-1 activity in H9 cells, whereas the other compounds were inactive. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.