Electronic Effects in a Green Protocol for (Hetero)Aryl-S Coupling

Aryl and heteroaryl iodides have been efficiently converted into the corresponding thioacetates in cyclopentyl methyl ether (CPME), a green solvent, under Cu catalysis. The chemoselectivity of the reaction is mainly controlled by electronic factors, enabling the conversion of both electron-rich and...

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Bibliographic Details
Published in:Molecules (Basel, Switzerland) Switzerland), 2024-04, Vol.29 (8), p.1714
Main Authors: Carraro, Massimo, Are, Camillo, Azzena, Ugo, De Luca, Lidia, Gaspa, Silvia, Satta, Giuseppe, Holzer, Wolfgang, Pace, Vittorio, Pisano, Luisa
Format: Article
Language:English
Subjects:
Ar-S coupling
Catalysis
Chemistry
CPME
Cu catalysis
Efficiency
electronic effects
Energy consumption
Environmental impact
green chemistry
Ligands
Polyphenylene sulphide
Potassium
Solvents
Sulfur
Thiols
Toxicity
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Summary:Aryl and heteroaryl iodides have been efficiently converted into the corresponding thioacetates in cyclopentyl methyl ether (CPME), a green solvent, under Cu catalysis. The chemoselectivity of the reaction is mainly controlled by electronic factors, enabling the conversion of both electron-rich and electron-deficient substrates into the corresponding thioacetates in good to excellent yields. The products can be easily deprotected to the corresponding thiolates to carry out additional synthetic transformations in situ. Surprisingly, despite CPME's relatively low dielectric constant, the reaction rate significantly increased when conducted under microwave irradiation conditions. This synthetic methodology exhibits a remarkable tolerance to functional groups, mild reaction conditions, and a wide substrate scope, utilizing a safe and inexpensive CuI pre-catalyst in the green solvent CPME. A non-aqueous workup allowing for the complete recovery of both catalyst and solvent makes this approach an environmentally sustainable protocol for C(sp ) sulfur functionalization. Additionally, the reaction shows selective cross-coupling with iodides in competition with chlorides and bromides, allowing its use in multistep syntheses. To demonstrate the potential of this methodology, it was applied to the high-yield synthesis of a photochromic dithienylethene, where a selective synthesis had not been reported before.
ISSN:1420-3049
1420-3049
DOI:10.3390/molecules29081714