New solutions to the C-12,13 stereo-problem of epothilones B and D; synthesis of a 12,13-diol-acetonide epothilone B analog

Gaich, Tanja; Karig, Gunter; Martin, Harry J.; Mulzer, Johann.   

European Journal of Organic Chemistry  (2006),   (15),  3372-3394. 

New approaches are described to the synthesis of epothilone B and a 12,13-diol-acetonide derivative. Specifically the (12Z) double bond is formed quantitatively by a silicon-tethered ring-closing metathesis (RCM) reaction with 85 % selectivity. Alternatively, a direct route to the 12,13-epoxide by cyclization of a 12,13-diol has been developed.