Shorter Route Refines Total Synthesis Of Anticancer Agent

A new enantioselective total synthesis of the natural product englerin A, a promising inhibitor of kidney cancer cell growth, requires fewer steps and has a better overall yield than previous routes. In 2009, the first enantioselective total synthesis of englerin A, in which its stereochemistry was determined, was achieved by Mathias Christmann of Dortmund University of Technology, in Germany, and coworkers (Angew. Chem. Int. Ed., DOI: 10.1002/anie.200905032; C&EN, Nov. 16, 2009, page 40). Several other englerin A syntheses have been reported since then. William J. Chain and coworkers at the University of Hawaii, Manoa, have now developed a version that is markedly more efficient (J. Am. Chem. Soc., DOI: 10.1021/ja201921j).With a convergent approach using readily available starting materials, the synthesis takes eight steps, compared with 15 for the previous shortest route, and it has 20% overall yield, compared with a previous best of 8%. Christmann comments that the new procedure “will allow for the synthesis of analogs that have not been accessible by previous syntheses and that might turn out to be effective in the identification of englerin’s molecular target.”