Studies on the regioselectivity of intermolecular diels-alder cycloadditions of 1-methylpyrano[3,4-b]indol-3-one and the N-acetylated derivative
作者:Helena Nandin de Carvalho、Gary I. Dmitrienko、Kent E. Nielson
DOI:10.1016/s0040-4020(01)87750-4
日期:1990.1
4-b]indol-3-one 1a with less than two equivalents of methyl acrylate and methyl vinyl ketone occur with complete regioselectivity to yield the corresponding 3-substituted 1-methyl-1,2-dihydrocarbazole derivatives 3.Cycloadditions of the N-acetyl-1-methylpyrano[3,4-b]indol-3-one 1b with the same dienophiles proceed at a much slower rate to yield adducts incorporating two molecules of the dienophile. In this
1-甲基吡喃并[3,4-b]吲哚-3-1a 1a与少于两个当量的丙烯酸甲酯和甲基乙烯基酮的Diels-Alder反应以完全区域选择性的方式发生,从而产生相应的3-取代的1-甲基-1 ,2-二氢咔唑衍生物3 .N-乙酰基-1-甲基吡喃并[3,4-b]吲哚-3-酮1b与相同的亲二烯体的环加成反应以慢得多的速率进行,从而产生掺入了两个亲二烯体分子的加合物。在这种情况下,由于作为主要产物获得的双加合物在C 2和C 2 '碳上具有取代基,因此在Diels-Alder反应的两个步骤中区域选择性似乎都已经反转。1a的反应用对称的亲二烯体富马酸二甲酯生成顺式和反式1-甲基-9H-1,2-二氢咔唑-2、3-二羧酸二甲基酯16和17的混合物,其比例分别为1:3.7。