Dimethylaluminum methide complex Tf2CHAlMe2: an effective catalyst for Diels–Alder reaction of α,β-unsaturated lactone derivatives with cyclopentadiene
作者:Hikaru Yanai、Arata Takahashi、Takeo Taguchi
DOI:10.1016/j.tet.2007.09.061
日期:2007.12
catalyst system for the catalytic DA reaction of less reactive α,β-unsaturated lactone derivative with cyclopentadiene (CP). In this catalyst system, Tf2CHAlMe2 is an active species and an excess amount of Me3Al plays an important role to lower the catalyst loading. Substituent effect of the lactone framework on π-facial selectivity was also examined. In the reactions of both γ-substituted 5-membered lactone
发现通过将Tf 2 CH 2和Me 3 Al混合而获得的路易斯酸是反应性较低的α,β-不饱和内酯衍生物与环戊二烯(CP)的催化DA反应的有效催化剂体系。在该催化剂体系中,Tf 2 CHAlMe 2是活性物质,过量的Me 3 Al在降低催化剂负载量方面起着重要作用。还研究了内酯骨架对π面选择性的取代作用。在γ取代的5元内酯衍生物和γ或δ甲基化的6元内酯衍生物与CP的反应中,对抗观察到γ-或δ-取代基的表面。另一方面,在γ-或γ-甲基化的7元内酯衍生物的情况下,CP有利地侵蚀了合成面上。