A novel copper-catalyzed, hydrazine-free synthesis of N-1 unsubstituted 1H-indazoles using stable guanylhydrazone salts as substrates. (2nd July 2021)

• Record Type: Journal Article
• Authors: Rekowski, Szymon P.; Kroener, Bettina K.; Kathuria, Deepika; Wani, Aabid A.; Chourasiya, Sumit S.; Conrad, Jürgen; Bharatam, Prasad V.; Frey, Wolfgang; Beifuss, Uwe
• Is Part Of: Tetrahedron. Volume 91(2021)
• Publication Date: 2021-07-02
• Subjects: 1H-indazole -- Copper-catalyzed -- NMR -- DFT -- Guanylhydrazone salts; Chemistry, Organic -- Periodicals; 547.005
• DOI: 10.1016/j.tet.2021.132192
• Languages: English
• ISSNs: 0040-4020

Abstract

Abstract: A CuI-catalyzed, hydrazine-free transformation of 2-(2-bromoarylidene)guanylhydrazone hydrochlorides using Cs2 CO3 as a base and DMEDA as a ligand at 120 °C for 5 h delivers substituted 1 H -indazoles with yields up to 75%. The C, N double bond configuration of the substrates was determined by NMR experiments and quantum chemical calculations. The reaction mechanism was studied using quantum chemical calculations. Graphical abstract: Image 1