Metal‐Free Oxidative B−N Coupling of nido‐Carborane with N‐Heterocycles. Issue 34 (9th July 2019)

• Record Type: Journal Article
• Authors: Yang, Zhongming; Zhao, Weijia; Liu, Wei; Wei, Xing; Chen, Meng; Zhang, Xiao; Zhang, Xiaolei; Liang, Yong; Lu, Changsheng; Yan, Hong
• Is Part Of: Angewandte Chemie international edition. Volume 58:Issue 34(2019)
• Page Start: 11886
• Page End: 11892
• Publication Date: 2019-07-09
• Subjects: cage compounds -- cross-coupling -- heterocycles -- reaction mechanisms -- synthetic methods; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201904940
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: A general method for the oxidative substitution of nido ‐carborane (7, 8‐C2 B9 H12 − ) with N‐heterocycles has been developed by using 2, 3‐dichloro‐5, 6‐dicyanobenzoquinone (DDQ) as an oxidant. This metal‐free B−N coupling strategy, in both inter‐ and intramolecular fashions, gave rise to a wide array of charge‐compensated, boron‐substituted nido ‐carboranes in high yields (up to 97 %) with excellent functional‐group tolerance under mild reaction conditions. The reaction mechanism was investigated by density‐functional theory (DFT) calculations. A successive single‐electron transfer (SET), B−H hydrogen‐atom transfer (HAT), and nucleophilic attack pathway is proposed. This method provides a new approach to nitrogen‐containing carboranes with potential applications in medicine and materials. Abstract : The metal‐free B−N coupling of nido ‐carboranes with various N‐heterocycles was studied. Both inter‐ and intramolecular reactions occur at ambient temperature, with high to excellent yields and high atom economy. DDQ=2, 3‐dichloro‐5, 6‐dicyanobenzoquinone, DME=1, 2‐dimethoxyethane.