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From the same journal

Dynamic Kinetic Sensitization of β-Dicarbonyl Compounds-Access to Medium-Sized Rings by De Mayo-Type Ring Expansion

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Published copy (DOI)

Author(s)

  • Tiffany O Paulisch
  • Lukas A Mai
  • Felix Strieth-Kalthoff
  • Michael J James
  • Christian Henkel
  • Dirk M Guldi
  • Frank Glorius

Department/unit(s)

Publication details

JournalAngewandte Chemie International Edition
DateAccepted/In press - 24 Nov 2021
DatePublished (current) - 26 Jan 2022
Issue number5
Volume61
Number of pages6
Original languageEnglish

Abstract

Herein, we present a photocatalyzed two-carbon ring expansion of β-dicarbonyl compounds with unactivated olefins that provides facile access to medium-sized rings. Selective sensitization of the substoichiometric enol tautomer enables reactivity of substrates incompatible with the classical De Mayo reaction conditions. Key to success is the identification of the metal-based sensitizer fac-[Ir(CF3 -pmb)3 ], which can be excited using common near-visible LEDs, and possesses a high triplet excited state energy of 73.3 kcal mol-1 . This exactly falls in the range between the triplet energies of the enol and keto tautomer, thereby enabling a dynamic kinetic sensitization. Demonstrating the applicability of fac-[Ir(CF3 -pmb)3 ] as a photocatalyst in organic synthesis for the first time, we describe a two-step photocycloaddition-ring-opening cascade with β-ketoesters, -diketones, and -ketoamides. The mechanism has been corroborated by time-resolved spectroscopy, as well as further experimental and computational studies.

Bibliographical note

© 2021 Wiley-VCH GmbH.

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