A General One‐Pot Synthesis of 2H‐Indazoles Using an Organophosphorus–Silane System. Issue 36 (6th June 2018)

• Record Type: Journal Article
• Authors: Schoene, Jens; Bel Abed, Hassen; Schmieder, Peter; Christmann, Mathias; Nazaré, Marc
• Is Part Of: Chemistry. Volume 24:Issue 36(2018)
• Page Start: 9090
• Page End: 9100
• Publication Date: 2018-06-06
• Subjects: cyclization -- domino reactions -- nitrogen heterocycles -- phosphorus -- regioselectivity; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201800763
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: A simple and direct approach for the regioselective construction of the privileged 2 H ‐indazole scaffold is described. The developed one‐pot strategy involves phospholene‐mediated N−N bond formation to access 2 H ‐indazoles. The amount of organophosphorus reagent was minimized by recycling the phospholene oxide with organosilane reductants. Starting from functionalized 2‐nitrobenzaldehydes and primary amines, a mild reductive cyclization, involving the use of commercially available phospholene oxide and silanes, delivered a wide variety of substituted 2 H ‐indazoles in good to excellent yields. Abstract : It's been a privilege : A simple mix‐and‐heat procedure enables rapid access to 2 H ‐indazoles as privileged scaffolds from 2‐nitrobenzaldehydes and primary amines by using a commercially available organophosphorus/silane system. Using this methodology, a library of 65 2 H ‐indazole derivatives carrying a broad range of substitution patterns is synthesized.