Asymmetric Diels–Alder reactions of 5-substituted and 5,6-disubstituted (S)-2-(p-tolylsulfinyl)-1,4-benzoquinones with cyclopentadiene and trans-piperylene
摘要:
A systematic study of reactions between 5-substituted and 5,6-disubstituted (S)-2-p-tolylsulfinyl-p-benzoquinones and cyclopentadiene or trans-piperylene is reported. Complete regio and pi-facial selectivities are observed. The different behaviours of cyclic and acyclic dienes in the presence of ZnBr2 (cyclopentadiene showed reversed diastereoselection) and the role of BF3 . OEt2 are discussed. (C) 1999 Elsevier Science Ltd. All rights reserved.