Azomethines, easily prepared from 5-(R)-furfurals and 1,3- or 1,2-amino alcohols (aminothiols), react under mild conditions with maleic anhydride affording 8,10a-epoxy[1,3]oxa(thia)-zino[2,3-a]isoindole-7- and 7,9a-epoxy[1,3]oxa(thia)zolo[2,3-a]isoindole-6-carboxylic acids. The reaction proceeds through initial N-acylation with subsequent intramolecular exo-Diels-Alder cycloaddition and stereoselectively leads to the exo adducts. The ‘one-pot’ synthetic protocol is also presented.
                                    由 5-(R)-
呋喃和 1,3- 或 1,2- 
氨基醇(
氨基
硫醇)制备的
偶氮甲烷很容易在温和的条件下与
马来酸酐反应,生成 8,10a-epoxy[1,3]oxa(thia)-zino[2,3-a]isoindole-7- 和 7,9a-epoxy[1,3]oxa(thia)zolo[2,3-a]isoindole-6- 
羧酸。该反应通过最初的 N-酰化和随后的分子内外向-Diels-Alder 环加成反应进行,并立体选择性地生成外向加合物。此外,还介绍了 "一锅 "合成方案。