Stereocontrolled Diels-Alder Reactions with Chiral Tricyclic Oxazolidinones.

Abstract (1 R ,2 R ,6 S ,7 S )-5-Aza-1,10,10-trimethyl-3-oxatricyclo[5.2.1.0 2,6 ]decan-4-one ( endo -oxazolidinone) and (1 R ,2 S ,6 R ,7 S )-isomer ( exo -oxazolidinone) are found to be efficient diastereomeric auxiliaries for Diels-Alder reactions, which are promoted by Lewis acid catalysts with predictable absolute stereochemistry. Thus, the reaction of cyclopentadiene with N -crotonyl-or N -cinnamoyl- endo -oxazolidinones gave (1 R ,2 R ,3 S .4 S )-3-methyl- or (1 R ,2 S ,3 S ,4 S )-3-phenylbicylo[2.2.1]hept-5-ene-2-carboxylates, while their enantiomers, i.e. (1 S ,2 S ,3 R ,4 R )-3-methyl- or (1 S ,2 R ,3 R ,4 R )-3-phenylbicyclo[2.2.1]hept-5-ene-2-carboxylates were obtained stereoselectively from the corresponding exo -oxazolidinone derivatives.