Asymmetric Synthesis of Spiropyrazolones by Sequential Organo‐ and Silver Catalysis. Issue 5 (16th December 2015)

• Record Type: Journal Article
• Authors: Hack, Daniel; Dürr, Alexander B.; Deckers, Kristina; Chauhan, Pankaj; Seling, Nico; Rübenach, Lukas; Mertens, Lucas; Raabe, Gerhard; Schoenebeck, Franziska; Enders, Dieter
• Is Part Of: Angewandte Chemie international edition. Volume 55:Issue 5(2016)
• Page Start: 1797
• Page End: 1800
• Publication Date: 2015-12-16
• Subjects: asymmetric synthesis -- Conia-ene reaction -- organocatalysis -- pyrazolones -- silver catalysis; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201510602
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: A stereoselective one‐pot synthesis of spiropyrazolones through an organocatalytic asymmetric Michael addition and a formal Conia‐ene reaction has been developed. Depending on the nitroalkene, the 5‐exo‐dig‐cyclization could be achieved by silver‐catalyzed alkyne activation or by oxidation of the intermediate enolate. The mechanistic pathways have been investigated using computational chemistry and mechanistic experiments. Abstract : Silver lining : A stereoselective one‐pot synthesis of spiropyrazolones through an organocatalytic asymmetric Michael addition and a formal Conia‐ene reaction has been developed. Silver catalysis plays a pivotal role for the cyclization, however metal‐free alternatives have been found in some cases. The mechanism was investigated by quantum chemical computations. H‐Do=hydrogen‐bonding donor.