Catalyst‐Free Decarbonylative Trifluoromethylthiolation Enabled by Electron Donor‐Acceptor Complex Photoactivation

A catalyst‐ and additive‐free decarbonylative trifluoromethylthiolation of aldehyde feedstocks has been developed. This operationally simple, scalable, and open‐to‐air transformation is driven by the selective photoexcitation of electron donor‐acceptor (EDA) complexes, stemming from the association...

Full description

Saved in:
Bibliographic Details
Published in:Advanced synthesis & catalysis 2021-07, Vol.363 (14), p.3507-3520
Main Authors: Lipp, Alexander, Badir, Shorouk O., Dykstra, Ryan, Gutierrez, Osvaldo, Molander, Gary A.
Format: Article
Language:English
Subjects:
Aldehydes
aldehydes, density functional calculations
Catalysts
Charge transfer
Coordination compounds
electron donor-acceptor complexes
Electron transfer
Electrons
Extreme values
photocatalysis
Photoexcitation
Phthalimides
Quantum mechanics
radical reactions
Thiocyanates
trifluoromethylthiolation
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:A catalyst‐ and additive‐free decarbonylative trifluoromethylthiolation of aldehyde feedstocks has been developed. This operationally simple, scalable, and open‐to‐air transformation is driven by the selective photoexcitation of electron donor‐acceptor (EDA) complexes, stemming from the association of 1,4‐dihydropyridines (donor) with N‐(trifluoromethylthio)phthalimide (acceptor), to trigger intermolecular single‐electron transfer events under ambient‐ and visible light‐promoted conditions. Extension to other electron acceptors enables the synthesis of thiocyanates and thioesters, as well as the difunctionalization of [1.1.1]propellane. The mechanistic intricacies of this photochemical paradigm are elucidated through a combination of experimental efforts and high‐level quantum mechanical calculations [dispersion‐corrected (U)DFT, DLPNO‐CCSD(T), and TD‐DFT]. This comprehensive study highlights the necessity for EDA complexation for efficient alkyl radical generation. Computation of subsequent ground state pathways reveals that SH2 addition of the alkyl radical to the intermediate radical EDA complex is extremely exergonic and results in a charge transfer event from the dihydropyridine donor to the N‐(trifluoromethylthio)phthalimide acceptor of the EDA complex. Experimental and computational results further suggest that product formation also occurs via SH2 reaction of alkyl radicals with 1,2‐bis(trifluoromethyl)disulfane, generated in‐situ through combination of thiyl radicals.
ISSN:1615-4150
1615-4169
DOI:10.1002/adsc.202100469