The chiralBrønstedacid (1b or 1c) has been shown to initiate the Hosomi−Sakurai reaction of imines with excellent enantioselectivities. The combined Brønstedacid system has been developed to offer a new class of chiralBrønstedacidcatalysis. The present system proceeds through regeneration of the chiralBrønstedacid by proton transfer from additional Brønstedacid to silylated chiral Brønsted
Chiral Phosphoric Acid Catalyzed Addition of Dihydropyrans to <i>N</i>-Acyl Imines: Stereocontrolled Access to Enantioenriched Spirocyclic Oxazoletetrahydropyrans with Three Contiguous Stereocenters
作者:Guilong Li、Matthew J. Kaplan、Lukasz Wojtas、Jon C. Antilla
DOI:10.1021/ol100378t
日期:2010.5.7
Dihydropyran derivatives readily undergo addition to N-acyl imines in the presence of chiral phosphoric acids. This addition process yields an attractive product that is capable of a tandem oxidative-cyclization via an epoxide intermediate.