Asymmetric total synthesis of paecilomycin E, 10′-epi-paecilomycin E and 6′-epi-cochliomycin CElectronic supplementary information (ESI) available. See DOI: 10.1039/c4ob01400f

The asymmetric total syntheses of naturally occurring resorcylic acid lactone paecilomycin E and two of its structural congeners have been reported in this article. The major highlight of the synthetic venture is the application of the late stage Mitsunobu macrolactonization method (as it is difficult to achieve the desired products through the standard carboxyl activation method) of a properly functionalized seco-acid. The macrolactonization precursor was synthesized by applying an " E "-selective Julia-Kocienski olefination of a highly functionalized aromatic aldehyde and a sulphone, which constitutes all the stereocenters (C4′, C5′, C6′ and C10′; 3 S ,7 R ,8 R ,9 S ) in the target molecule. The asymmetric total syntheses of paecilomycin E and its stereoisomers have been disclosed by employing the late stage Mitsunobu macrolactonization reaction.