Stereodivergent Synthesis of Tetrahydrofuroindoles through Pd-Catalyzed Asymmetric Dearomative Formal [3+2]
Qiang Cheng1, Fang Zhang1, Yue Cai1
1State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Lu, Shanghai, 200032, China.
Abstract:
A stereodivergent synthesis of tetrahydrofuroindoles through palladium-catalyzed asymmetric dearomative formal [3+2] cycloaddition of nitroindoles with epoxybutenes was developed. The polarity of the solvent was found to play a key role in the diastereoselectivity. In toluene, good to excellent yields (70-99 %), diastereoselectivity (87/13->95/5 d.r.), and enantioselectivity (85/15-94/6 e.r.) were obtained, regardless of the properties of the substituents on nitroindoles. In acetonitrile, tetrahydrofuroindoles of a different diastereoisomer were produced with good to excellent yields (75-98 %) and stereoselectivity (78/22-93/7 d.r., 93/7-99/1 e.r.). Mechanistic studies were conducted to illustrate the origin of the diastereodivergency. The kinetic experiments indicate that the rate-determining step of this reaction is different in different solvents. ESI-MS experiments also support the existence of key palladium complex intermediates and the catalytic cycle of the reaction.
More Related Videos
Related Concept Videos
Formal Charges
[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction
ortho–para-Directing Activators: –CH3, –OH, –⁠NH2, –OCH3
Transfer RNA Synthesis
Each of these chemical modifications is carried by a specific enzyme, post-transcription. All of these enzymes have unique base and site-specificity. Methylation, the most common chemical modification, is carried by at least nine different enzymes, with...
Lewis Structures and Formal Charges
Cycloaddition Reactions: Overview


![The Synthesis of [Sn10SiSiMe334]2- Using a Metastable SnI Halide Solution Synthesized via a Co-condensation Technique](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F54498.jpg&w=3840&q=50)