Unexpected Electrophilic Rearrangements of Amides: A Stereoselective Entry to Challenging Substituted Lactones
作者:Claire Madelaine、Viviana Valerio、Nuno Maulide
DOI:10.1002/anie.200906416
日期:2010.2.22
Surprise, surprise! An unexpected skeletal rearrangement was developed into a chemo‐ and stereoselective synthesis of α‐allyl and allenyl lactones with challenging substitution patterns (see scheme; EWG=electron‐withdrawing group). The generality, unique features, and synthetic potential of this reaction were probed and a mechanism was proposed.
The Tsuji–Trost protocol has been successfully employed for the allylicalkylation of preformed lactone enolates. It has been demonstrated that this Pd‐catalyzed reaction can be carried out in an enantio‐ and diastereoselective manner. The use of additives, such as LiCl, was found to be crucial for reaching high levels of product selectivity. For one particular pair of reactants, density functional