ASYMMETRIC DIELS-ALDER ADDITION OF CYCLOPENTADIENE TO CHIRAL NAPHTHOQUINONES

Diels-Alder reactions of 1,4-naphthoquinones bearing a chiral auxiliar y at C-2, with cyclopentadiene under Lewis acid conditions afforded th e corresponding Diels-Alder. adducts. High levels of diastereomeric ex cess were obtained using (R)-pantolactone, (S)-N-methyl-2-hydroxysucci nimide and trans-2-phenylcyclohexanol as auxiliaries. Moderate asymmet ric induction was achieved using Oppolzer's camphorsultam and (R)-(+)- 4-benzyl-2-oxazolidinone as auxiliaries. X-Ray crystallographic analys is of the pantolactone adduct enabled determination of the stereochemi stry of all adducts obtained. (C) 1998 Elsevier Science Ltd. All right s reserved.