Coumarin C−H Functionalization by Mn(I) Carbonyls: Mechanistic Insight by Ultra-Fast IR Spectroscopic Analysis

Thomas J. Burden; Kathryn P.R. Fernandez; Mary Kagoro; Jonathan B. Eastwood; Theo F.N. Tanner; Adrian C. Whitwood; Ian P. Clark; Michael Towrie; Jean Philippe Krieger; Jason M. Lynam; Ian J.S. Fairlamb

doi:10.1002/chem.202203038

Coumarin C−H Functionalization by Mn(I) Carbonyls: Mechanistic Insight by Ultra-Fast IR Spectroscopic Analysis

Thomas J. Burden, Kathryn P.R. Fernandez, Mary Kagoro, Jonathan B. Eastwood, Theo F.N. Tanner, Adrian C. Whitwood, Ian P. Clark, Michael Towrie, Jean Philippe Krieger, Jason M. Lynam^*, Ian J.S. Fairlamb

^*Corresponding author for this work

Chemistry

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

Abstract

Mn(I) C−H functionalization of coumarins provides a versatile and practical method for the rapid assembly of fused polycyclic pyridinium-containing coumarins in a regioselective manner. The synthetic strategy enables application of bench-stable organomanganese reagents in both photochemical- and thermal-promoted reactions. The cyclomanganated intermediates, and global reaction system, provide an ideal testing ground for structural characterization of the active Mn(I) carbonyl-containing species, including transient species observable by ultra-fast time-resolved spectroscopic methods. The thermodynamic reductive elimination product, solely encountered from reaction between alkynes and air-stable organometallic cyclomanganated coumarins, has enabled characterization of a critical seven-membered Mn(I) intermediate, detected by time-resolved infrared spectroscopy, enabling the elucidation of the temporal profile of key steps in the reductive elimination pathway. Quantitative data are provided. Manganated polycyclic products are readily decomplexed by AgBF₄, opening-up an efficient route to the formation of π-extended hybrid coumarin-pyridinium compounds.

Original language	English
Article number	e202203038
Number of pages	8
Journal	Chemistry - A European Journal
Early online date	23 Mar 2023
DOIs	https://doi.org/10.1002/chem.202203038
Publication status	E-pub ahead of print - 23 Mar 2023

Bibliographical note

Funding Information:
The STFC (access to the ULTRA facility at the Rutherford Appleton Laboratories, Harwell UK) is gratefully acknowledged for funding, equipment, and support. We thank Syngenta (CASE award) for co‐funding an EPSRC CASE PhD studentship for T.J.B (doctoral training grant reference EP/ N509413/1), the University of York for a PhD studentship to J.B.E, the Royal Society of Chemistry for a research enablement grant (E21‐8424864227) and EPSRC for a responsive mode grant (EP/W031914/1). The Schlumberger Foundation is gratefully acknowledged for funding to support the PhD studies of M.K. We thank David Husbands for assistance with C NMR experiments. J.M.L. and I.J.S.F. acknowledge the Royal Society for Industry Fellowships (INF\R1\221057 and INF\R2\202122 respectively). The computational work in this project was undertaken on the Viking Cluster, which is a high‐performance computer facility provided by the University of York. We are grateful for computational support from the University of York High Performance Computing service, Viking and the Research Computing team. 13

Publisher Copyright:
© 2023 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.

Keywords

coumarin
cyclomanganation
infrared spectroscopy
manganese
organomanganese

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Chemistry A European J - 2023 - Burden - Coumarin C H Functionalization by Mn I Carbonyls Mechanistic Insight by
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Burden, T. J., Fernandez, K. P. R., Kagoro, M., Eastwood, J. B., Tanner, T. F. N., Whitwood, A. C., Clark, I. P., Towrie, M., Krieger, J. P., Lynam, J. M., & Fairlamb, I. J. S. (2023). Coumarin C−H Functionalization by Mn(I) Carbonyls: Mechanistic Insight by Ultra-Fast IR Spectroscopic Analysis. Chemistry - A European Journal, Article e202203038. Advance online publication. https://doi.org/10.1002/chem.202203038

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title = "Coumarin C−H Functionalization by Mn(I) Carbonyls: Mechanistic Insight by Ultra-Fast IR Spectroscopic Analysis",

abstract = "Mn(I) C−H functionalization of coumarins provides a versatile and practical method for the rapid assembly of fused polycyclic pyridinium-containing coumarins in a regioselective manner. The synthetic strategy enables application of bench-stable organomanganese reagents in both photochemical- and thermal-promoted reactions. The cyclomanganated intermediates, and global reaction system, provide an ideal testing ground for structural characterization of the active Mn(I) carbonyl-containing species, including transient species observable by ultra-fast time-resolved spectroscopic methods. The thermodynamic reductive elimination product, solely encountered from reaction between alkynes and air-stable organometallic cyclomanganated coumarins, has enabled characterization of a critical seven-membered Mn(I) intermediate, detected by time-resolved infrared spectroscopy, enabling the elucidation of the temporal profile of key steps in the reductive elimination pathway. Quantitative data are provided. Manganated polycyclic products are readily decomplexed by AgBF4, opening-up an efficient route to the formation of π-extended hybrid coumarin-pyridinium compounds.",

keywords = "coumarin, cyclomanganation, infrared spectroscopy, manganese, organomanganese",

author = "Burden, {Thomas J.} and Fernandez, {Kathryn P.R.} and Mary Kagoro and Eastwood, {Jonathan B.} and Tanner, {Theo F.N.} and Whitwood, {Adrian C.} and Clark, {Ian P.} and Michael Towrie and Krieger, {Jean Philippe} and Lynam, {Jason M.} and Fairlamb, {Ian J.S.}",

note = "Funding Information: The STFC (access to the ULTRA facility at the Rutherford Appleton Laboratories, Harwell UK) is gratefully acknowledged for funding, equipment, and support. We thank Syngenta (CASE award) for co‐funding an EPSRC CASE PhD studentship for T.J.B (doctoral training grant reference EP/ N509413/1), the University of York for a PhD studentship to J.B.E, the Royal Society of Chemistry for a research enablement grant (E21‐8424864227) and EPSRC for a responsive mode grant (EP/W031914/1). The Schlumberger Foundation is gratefully acknowledged for funding to support the PhD studies of M.K. We thank David Husbands for assistance with C NMR experiments. J.M.L. and I.J.S.F. acknowledge the Royal Society for Industry Fellowships (INF\R1\221057 and INF\R2\202122 respectively). The computational work in this project was undertaken on the Viking Cluster, which is a high‐performance computer facility provided by the University of York. We are grateful for computational support from the University of York High Performance Computing service, Viking and the Research Computing team. 13 Publisher Copyright: {\textcopyright} 2023 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.",

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doi = "10.1002/chem.202203038",

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AU - Fernandez, Kathryn P.R.

AU - Kagoro, Mary

AU - Eastwood, Jonathan B.

AU - Tanner, Theo F.N.

AU - Whitwood, Adrian C.

AU - Clark, Ian P.

AU - Towrie, Michael

AU - Krieger, Jean Philippe

AU - Lynam, Jason M.

AU - Fairlamb, Ian J.S.

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N2 - Mn(I) C−H functionalization of coumarins provides a versatile and practical method for the rapid assembly of fused polycyclic pyridinium-containing coumarins in a regioselective manner. The synthetic strategy enables application of bench-stable organomanganese reagents in both photochemical- and thermal-promoted reactions. The cyclomanganated intermediates, and global reaction system, provide an ideal testing ground for structural characterization of the active Mn(I) carbonyl-containing species, including transient species observable by ultra-fast time-resolved spectroscopic methods. The thermodynamic reductive elimination product, solely encountered from reaction between alkynes and air-stable organometallic cyclomanganated coumarins, has enabled characterization of a critical seven-membered Mn(I) intermediate, detected by time-resolved infrared spectroscopy, enabling the elucidation of the temporal profile of key steps in the reductive elimination pathway. Quantitative data are provided. Manganated polycyclic products are readily decomplexed by AgBF4, opening-up an efficient route to the formation of π-extended hybrid coumarin-pyridinium compounds.

AB - Mn(I) C−H functionalization of coumarins provides a versatile and practical method for the rapid assembly of fused polycyclic pyridinium-containing coumarins in a regioselective manner. The synthetic strategy enables application of bench-stable organomanganese reagents in both photochemical- and thermal-promoted reactions. The cyclomanganated intermediates, and global reaction system, provide an ideal testing ground for structural characterization of the active Mn(I) carbonyl-containing species, including transient species observable by ultra-fast time-resolved spectroscopic methods. The thermodynamic reductive elimination product, solely encountered from reaction between alkynes and air-stable organometallic cyclomanganated coumarins, has enabled characterization of a critical seven-membered Mn(I) intermediate, detected by time-resolved infrared spectroscopy, enabling the elucidation of the temporal profile of key steps in the reductive elimination pathway. Quantitative data are provided. Manganated polycyclic products are readily decomplexed by AgBF4, opening-up an efficient route to the formation of π-extended hybrid coumarin-pyridinium compounds.

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KW - infrared spectroscopy

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DO - 10.1002/chem.202203038

M3 - Article

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JO - Chemistry - A European Journal

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ER -

Coumarin C−H Functionalization by Mn(I) Carbonyls: Mechanistic Insight by Ultra-Fast IR Spectroscopic Analysis

Abstract

Bibliographical note

Keywords

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