Oxazaborolidinone-Catalyzed Enantioselective Diels−Alder Reaction of Acyclic α,β-Unsaturated Ketones SinghRam Shanker AdachiShinya TanakaFumi YamauchiToyonao InuiChieko HaradaToshiro 2008 <i>allo</i>-Threonine-derived <i>O-</i>acyl-<i>B</i>-phenyl-oxazaborolidinones are demonstrated to be powerful and highly enantioselective 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−Alder adducts are obtained in 76−98% ee with high <i>endo</i>-selectivity. The catalyst exhibits high activity for the reaction with the less reactive β-substituted dienophiles and the less reactive 1,3-cycohexadiene and 1,3-butadiene derivatives. The application of the catalysts to the Diels−Alder reaction of furan is also described.