A new and convenient chiral auxiliary for asymmetric Diels-Alder cycloadditions in environmentally benign solvents

Preliminary investigations of asymmetric Diels-Alder reactions using a new chiral auxiliary are presented. The auxiliary is readily prepared from an aldehyde and asparagine in water. The resulting heterocycle is coupled with acryloyl chloride in the same pot to provide chiral dienophiles. These are reacted with cyclopentadiene at room temperature in water or ethanol-water to provide cycloaddition adducts diastercoselectively, as demonstrated by chiral HPLC of saponification products 5-norbornene-2-carboxylic acids (47-64% ee for the endo isomers; endo/exo 82:18).