Intermediates for the synthesis of epothilones and methods for their preparation
申请人:Novartis AG
公开号:US06350878B1
公开(公告)日:2002-02-26
The invention relates to a method of synthesis for a compound of formula (I),
wherein R is a heterocyclyl moiety and X1, X2, X3 and X4 are, independently of each other, protecting groups, which is appropriate for the synthesis of epothilone B and desoxyepothione B.
Synthesis of .alpha.,.alpha.,.beta.,.beta.-Tetrasubstituted .beta.-Lactones from Ketones, Ethyl .alpha.-Bromoisobutyrate, and Indium or Zinc. Factors Influencing the .beta.-Lactone Formation in the Electrochemical and the Classical Procedure of the Reformatsky Reaction
An efficient synthesis of alpha,alpha,beta,beta-tetrasubstituted beta-lactones is achieved by an electrochemically supported Reformatsky reaction of aliphatic and aromatic ketones with ethyl alpha-bromoisobutyrate at a sacrificial indium anode. Under these conditions, in most cases the expected beta-hydroxy esters are formed only in negligible amounts or not at all. beta-Lactones are also obtained with a sacrificial zinc anode or even with indium or zinc powder. The substitution pattern of the reactants, the polarity of the solvent, and the applied metal are recognized as factors influencing the extent of the beta-lactone formation.
Total Synthesis of (−)-Epothilone A
作者:Dieter Schinzer、Armin Bauer、Oliver M. Böhm、Anja Limberg、Martin Cordes