Electrochemically driven strain-release dearomative (3 + 2) cyclization for the synthesis of
Yanren Zhu1, Enfan Pu1, Shaoxiong Yang1
1Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education, Yunnan Key Laboratory of Cross-Border Infectious Disease Control and Prevention and Novel Drug Development, School of Chemical Science and Technology, School of Pharmacy, Yunnan University Kunming 650500 China zhanghb@ynu.edu.cn chenjb@ynu.edu.cn.
Researchers developed an electrochemical method to synthesize complex spiroindolines from bicyclo[1.1.0]butane-substituted indoles. This efficient strategy creates novel polycyclic compounds with multiple stereocenters, valuable for medicinal chemistry.
Area of Science:
- Organic Chemistry
- Synthetic Chemistry
- Electrochemistry
Background:
- Spiroindolines are crucial in natural products and bioactive compounds.
- Synthesizing complex, C(sp3)-rich polycyclic molecules with quaternary centers is challenging.
Purpose of the Study:
- To develop an efficient and green electrochemical method for spiroindoline synthesis.
- To construct novel bicyclo[2.1.1]hexane-fused polycyclic spiroindolines.
Main Methods:
- Electrochemical dearomative (3 + 2) cyclization of C3-bicyclo[1.1.0]butane (BCB)-substituted indoles.
- Mild reaction conditions, no external oxidants required.
Main Results:
- Efficient assembly of complex bicyclo[2.1.1]hexane (BCH)-fused polycyclic spiroindolines.
- High yields of products with four contiguous stereogenic centers, including two spirocyclic all-carbon quaternary centers.
- Products are versatile for further transformations.
Conclusions:
- This electrochemical strategy offers a practical and atom-economic route to valuable spiroindolines.
- The synthesized C(sp3)-rich compounds hold potential for medicinal chemistry applications.
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Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
Diels–Alder Reaction Forming Cyclic Products: Stereochemistry
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