A Stereoselective Oxidative Dimerization En Route to (-)-Lomaiviticin A.

We describe a stereoselective synthesis of the dimeric diazofluorene , a potential precursor to the cytotoxic -symmetric bacterial metabolite (-)-lomaiviticin A (). An efficient route was developed to convert the tetracyclic diol to the diketone (five steps, 30% overall). Oxidative dimerization of the enoxysilane provided the -symmetric dimeric diazofluorene in 56% yield and with 15:1:0 diastereoselectivity. Deprotection and 2D NMR analysis indicated that the major diastereomer possessed the (2,2') configuration found in . This approach may ultimately be useful in the synthesis of itself.