New carbohydrate-based chiral auxiliaries in Diels–Alder reaction
作者:Maria L.G. Ferreira、Sergio Pinheiro、Clarissa C. Perrone、Paulo R.R. Costa、Vı́tor F. Ferreira
DOI:10.1016/s0957-4166(98)00286-9
日期:1998.8
The carbohydrate derivatives 1–5 were evaluated as chiralauxiliaries in the Diels–Alderreaction of its acrylate derivatives 6a–e with cyclopentadiene promoted by Lewis acids. Although excellent endo:exo ratios (98:2) were obtained in many cases, the π-facial selectivities were from low to moderate (up to 60% d.e.). An effect of non-coordinating solvents reversing the stereoselectivities of adducts