[Co(MeTAA)] Metalloradical Catalytic Route to Ketenes via Carbonylation of Carbene Radicals

2018/02/21 by Andrei Chirila, Kaj M. van Vliet, Nanda D. Paul +1 · 1 citation
Chemistry · #Cyclopropane Reaction Mechanisms #Catalytic C–H Functionalization Methods #Synthesis and Catalytic Reactions

paper · pdf · doi:10.1002/ejic.201800101

openalex publication_date 2018/02/21 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01

Abstract

An efficient synthetic strategy towards beta‐lactams, amides, and esters involving “in situ” generation of ketenes and subsequent trapping with nucleophiles is presented. Carbonylation of carbene radical intermediates using the cheap and highly active cobalt(II) tetramethyltetraaza[14]annulene catalyst [Co(MeTAA)] provides a convenient one‐pot synthetic protocol towards substituted ketenes. N ‐tosylhydrazones are used as carbene precursors, thereby bridging the gap between aldehydes and ketenes. Activation of these carbene precursors by the metalloradical cobalt(II) catalyst affords Co III ‐carbene radicals, which subsequently react with carbon monoxide to form ketenes. In the presence of a nucleophile (imine, alcohol, or amine) in the reaction medium the ketene is immediately trapped, resulting in the desired products in a one‐pot synthetic protocol. The β‐lactams formed upon reaction with imines are produced in a highly trans ‐selective manner.

Citations

• The Development of the First Catalyzed Reaction of Ketenes and Imines: Catalytic, Asymmetric Synthesis of β-Lactams
• The Use of Tosylhydrazone Salts as a Safe Alternative for Handling Diazo Compounds and Their Applications in Organic Synthesis
• Ein Jahrhundert Ketene (1905–2005): die Entdeckung einer vielseitigen Klasse reaktiver Intermediate

Cited by

• Ketene [wikipedia]