Catalyst-Controlled Chemodivergent Reactions of 2-Pyrrolyl-α-diazo-β-ketoesters and Enol Ethers: Synthesis of 1,2-Dihydrofuran Acetals and Highly Substituted Indoles
作者:Gabriel Guerra Faura、Tena Nguyen、Stefan France
DOI:10.1021/acs.joc.1c00826
日期:2021.8.6
chemodivergent reaction of pyrrolyl-α-diazo-β-ketoesters with enol ethers is reported. While Cu(II) catalysts selectively promoted a [3 + 2] cycloaddition to provide pyrrolyl-substituted 2,3-dihydrofuran (DHF) acetals, dimeric Rh(II) catalysts afforded 6-hydroxyindole-7-carboxylates via an unreported [4 + 2] benzannulation. The choice of enol ether proved to be crucial in determining both regioselectivity
报道了吡咯基-α-重氮-β-酮酯与烯醇醚的催化剂控制的化学发散反应。虽然 Cu(II) 催化剂选择性地促进 [3 + 2] 环加成以提供吡咯基取代的 2,3-二氢呋喃 (DHF) 缩醛,但二聚 Rh(II) 催化剂通过未报道的 [4 + 2]苯环化。事实证明,烯醇醚的选择对于确定相应产物的区域选择性和产率至关重要(Cu(II) 的产率高达 91%,Rh(II) 催化的产率高达 82%)。此外,在路易斯酸的存在下,DHF 缩醛被证明可以作为 7-羟基吲哚-6-羧酸酯(由 Rh 形成的吲哚的异构体)和高度取代的呋喃的前体。因此,从常见的吡咯基-α-重氮-β-酮酯,