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

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

doi:10.1002/anie.202112695

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

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

Chemistry

Research output: Contribution to journal › Article › peer-review

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.

Original language	English
Article number	e202112695
Number of pages	6
Journal	Angewandte Chemie International Edition
Volume	61
Issue number	5
DOIs	https://doi.org/10.1002/anie.202112695
Publication status	Published - 26 Jan 2022

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

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.",

author = "Paulisch, {Tiffany O} and Mai, {Lukas A} and Felix Strieth-Kalthoff and James, {Michael J} and Christian Henkel and Guldi, {Dirk M} and Frank Glorius",

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T1 - Dynamic Kinetic Sensitization of β-Dicarbonyl Compounds-Access to Medium-Sized Rings by De Mayo-Type Ring Expansion

AU - Paulisch, Tiffany O

AU - Mai, Lukas A

AU - Strieth-Kalthoff, Felix

AU - James, Michael J

AU - Henkel, Christian

AU - Guldi, Dirk M

AU - Glorius, Frank

PY - 2022/1/26

Y1 - 2022/1/26

N2 - 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.

AB - 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.

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