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

Autor: Burden TJ; Department of Chemistry, University of York Heslington, York, YO10 5DD, UK., Fernandez KPR; Department of Chemistry, University of York Heslington, York, YO10 5DD, UK., Kagoro M; Department of Chemistry, University of York Heslington, York, YO10 5DD, UK., Eastwood JB; Department of Chemistry, University of York Heslington, York, YO10 5DD, UK., Tanner TFN; Department of Chemistry, University of York Heslington, York, YO10 5DD, UK., Whitwood AC; Department of Chemistry, University of York Heslington, York, YO10 5DD, UK., Clark IP; Central Laser Facility, Research Complex at Harwell STFC Rutherford Appleton Laboratory Harwell Campus Didcot, Oxfordshire, OX11 0QX, UK., Towrie M; Central Laser Facility, Research Complex at Harwell STFC Rutherford Appleton Laboratory Harwell Campus Didcot, Oxfordshire, OX11 0QX, UK., Krieger JP; Syngenta Crop Protection AG, Breitenloh 5, 4333, Münchwilen, Switzerland., Lynam JM; Department of Chemistry, University of York Heslington, York, YO10 5DD, UK., Fairlamb IJS; Department of Chemistry, University of York Heslington, York, YO10 5DD, UK.
Jazyk: angličtina
Zdroj: Chemistry (Weinheim an der Bergstrasse, Germany) [Chemistry] 2023 May 02; Vol. 29 (25), pp. e202203038. Date of Electronic Publication: 2023 Mar 23.
DOI: 10.1002/chem.202203038
Abstrakt: 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 AgBF 4 , opening-up an efficient route to the formation of π-extended hybrid coumarin-pyridinium compounds.
(© 2023 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)
Databáze: MEDLINE
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