ASYMMETRIC SYNTHESIS OF 2-EXO-AMINONORBORNANE-2-ENDO-CARBOXYLIC ACID DERIVATIVES

Article abstract of DOI:10.1016/S0957-4166(00)82170-9

The Diels-Alder reaction of cyclopentadiene with N-acetyl-α,β-didehydroalaninate of (-)-cis-3-hydroxy isobornyl neopentyl ether yields the corresponding 2-endo(exo)-acetamido-5-norbornene-2-exo(endo)-carboxylates with total diastereofacial selectivity and with a preference for the cycloadduct with the ester group placed at the endo position.So this dienophile is complementary with the previously described (-)-menthyl N-acetyl-α,β-didehydroalaninate for the asymmetric synthesis of 2-aminonorbornane-2-carboxylic acids, since with the latter dienophile exo cycloadducts are preferably obtained with a high diastereofacial selectivity.