A surprising mechanistic "switch" in Lewis acid activation: a bifunctional, asymmetric approach to alpha-hydroxy acid derivatives.

@article{Abraham2008ASM,
  title={A surprising mechanistic "switch" in Lewis acid activation: a bifunctional, asymmetric approach to alpha-hydroxy acid derivatives.},
  author={Ciby J. Abraham and Daniel H. Paull and Tefsit Bekele and Michael T. Scerba and Travis Dudding and Thomas Lectka},
  journal={Journal of the American Chemical Society},
  year={2008},
  volume={130 50},
  pages={17085-94}
}
We report a detailed synthetic and mechanistic study of an unusual bifunctional, sequential hetero-Diels-Alder/ring-opening reaction in which chiral, metal complexed ketene enolates react with o-quinones to afford highly enantioenriched, alpha-hydroxylated carbonyl derivatives in excellent yield. A number of Lewis acids were screened in tandem with cinchona alkaloid derivatives; surprisingly, trans-(Ph(3)P)(2)PdCl(2) was found to afford the most dramatic increase in yield and rate of reaction… CONTINUE READING