Copper‐Catalyzed Oxyboration of Unactivated Alkenes. Issue 45 (17th September 2015)

• Record Type: Journal Article
• Authors: Itoh, Taisuke; Matsueda, Takumi; Shimizu, Yohei; Kanai, Motomu
• Is Part Of: Chemistry. Volume 21:Issue 45(2015)
• Page Start: 15955
• Page End: 15959
• Publication Date: 2015-09-17
• Subjects: alkenes -- copper -- difunctionalization -- boration -- radical reactions; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201503329
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: The first regiodivergent oxyboration of unactivated terminal alkenes is reported, using copper alkoxide as a catalyst, bis(pinacolato)diboron [(Bpin)2 ] as a boron source, and (2, 2, 6, 6‐tetramethylpiperidin‐1‐yl)oxyl (TEMPO) as an oxygen source. The reaction is compatible with various functional groups. Two regioisomers are selectively produced by selecting the appropriate ligands on copper. The products may be used as a linchpin precursor for various other functionalizations, and net processes such as carbooxygenation, aminooxygenation, and dioxygenation of alkenes can be achieved after CB bond transformations. Mechanistic studies indicate that the reaction involves the following steps: 1) Transmetalation between CuO t Bu and (Bpin)2 to generate a borylcopper species; 2) regiodivergent borylcupration of alkenes; 3) oxidation of the thus‐generated CCu bond to give an alkyl radical; 4) trapping of the resulting alkyl radical by TEMPO. Abstract : The first oxyboration of alkenes has been realized using copper alkoxide as a catalyst, (Bpin)2 as a boron source, and 2, 2, 6, 6‐tetramethylpiperidine N ‐oxide (TEMPO) as an oxygen source. The oxyboration proceeds through a unique mechanism involving both nucleophilic and one‐electron redox‐active properties of copper catalysis. Regiodivergent oxyboration of alkenes is enabled by selecting appropriate ligands on copper.