A synthetic approach to the C17-benzene ansamycins via metal catalyzed C− C coupling is described. Key bond formations include direct iridium catalyzed carbonyl crotylation from the alcohol oxidation level followed by chelation-controlled Sakurai− Seyferth dienylation to form the stereotriad, which is attached to the arene via Suzuki cross-coupling. The diene- containing carboxylic acid is prepared using rhodium catalyzed acetylene-aldehyde ...
