Total Synthesis of (-)-8-O-methyltetrangomycin (MM 47755)

A stereoselective total synthesis of the natural antibiotic (-)-8-O-methyltetrangomycin 1 is reported. The essential steps for this convergent synthesis are the transformation of a geraniol epoxide into a chiral octadiyne derivative, which was converted into a triyne. The cobalt-mediated [2+2+2]cycloaddition of the triyne led to a benz[ a] anthracene system, which was oxidized with Ag( Py)(2)MnO4 to a benz[ a] anthraquinone. Deprotection with aqueous HF in acetonitrile and photooxidation afforded the desired product (-)-1.