A gold-catalyzed tandem annulation of propargylic alcohols and pyridylhomopropargylic alcohols is achieved, providing an atom-economical approach to a diverse set of polycyclic dihydrobenzofurans in good yields. The reaction proceeds via the 5-endo-dig cyclization/Meyer–Schuster rearrangement/Friedel–Crafts-type pathway. In this way, three C–C bonds and one C–O bond form to give a polycyclic skeleton
Cooperative Palladium/Brønsted Acid Catalysis toward the Highly Enantioselective Allenylation of β-Keto Esters
作者:Henning J. Loui、Christoph Schneider
DOI:10.1021/acs.orglett.2c00179
日期:2022.2.25
We report the first enantioselective allenylation of Pd enolates enabled by cooperative Pd/Brønsted acid catalysis employing β-keto esters and propargyl alcohols. The enantioselectivity originates solely from an in-situ-generated chiral metal enolate in an open transition state with no additional binding of the propargyl component to the catalyst. Thus a broad substrate scope was established, furnishing
Ca(II)-Catalyzed Cascade Reaction of Tryptamines with Propargylic Alcohols: Temperature-Driven Ring Opening and Closing via the Allene Migration Pathway for the Synthesis of Pyrrolo[1,2-<i>a</i>]indoles
作者:Ashok Kale、Su Jeong Kwon、Joohan Lee、Jae Kyun Lee、Kyeong Lee
DOI:10.1021/acs.orglett.3c04357
日期:2024.2.16
temperature-dependent cascade of reactions between tryptamines and propargylicalcohols was developed to achieve selective formation of pyrroloindoline and pyrrolo[1,2-a]indole heterocycles by Ca(II) catalysis. The cascade consists of electrophilic addition of allene at the C3 carbon of indole followed by intramolecular cyclization at 60 °C to yield pyrroloindolines. Furthermore, simultaneous 1,2-allene
开发了色胺和炔丙醇之间的温度依赖性级联反应,以通过 Ca(II) 催化选择性形成吡咯并吲哚啉和吡咯并[1,2- a ]吲哚杂环。该级联包括在吲哚的 C3 碳上进行丙二烯的亲电加成,然后在 60 °C 下进行分子内环化,生成吡咯并吲哚啉。此外,同时进行1,2-丙二烯迁移和吡咯烷开环,然后在回流温度下通过C-N键形成进行分子内环化,以获得吡咯并[1,2- a ]吲哚支架。该方案的优点是底物范围广泛、反应过程干净、可扩展性以及良好至优异的产率。