| Abstract
| - allo-Threonine-derived O-acyl-B-phenyl-oxazaborolidinones are demonstrated to be powerful and highlyenantioselective Lewis acid catalysts for the Diels−Alder reaction of simple acyclic enone dienophiles,expanding the scope of ketone dienophiles and dienes. With 10 to 20 mol % of catalyst, the Diels−Alderadducts are obtained in 76−98% ee with high endo-selectivity. The catalyst exhibits high activity for thereaction with the less reactive β-substituted dienophiles and the less reactive 1,3-cycohexadiene and1,3-butadiene derivatives. The application of the catalysts to the Diels−Alder reaction of furan is alsodescribed.
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