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

Area of Science:

• Organic Chemistry
• Green Chemistry
• Catalysis

Background:

• Aryl and heteroaryl iodides are important building blocks in organic synthesis.
• Developing efficient and sustainable methods for their functionalization is crucial.
• Existing methods may lack selectivity or require harsh conditions.

Purpose of the Study:

• To develop a novel, green, and efficient method for synthesizing thioacetates from aryl and heteroaryl iodides.
• To explore the scope and limitations of the developed methodology.
• To demonstrate the utility of the method in synthesizing complex organic molecules.

Main Methods:

• Copper-catalyzed thioacetylation of aryl and heteroaryl iodides.
• Utilized cyclopentyl methyl ether (CPME) as a green solvent.
• Investigated the effect of microwave irradiation on reaction rates.
• Demonstrated in situ deprotection of thioacetates to thiolates.

Main Results:

• Achieved efficient conversion of diverse aryl and heteroaryl iodides to thioacetates in good to excellent yields.
• The reaction demonstrated high chemoselectivity, controlled by electronic factors.
• Microwave irradiation significantly accelerated the reaction rate in CPME.
• The methodology showed excellent functional group tolerance and selectivity over chlorides and bromides.
• Successfully synthesized a photochromic dithienylethene precursor in high yield.

Conclusions:

• Developed a sustainable and efficient protocol for C(sp2) sulfur functionalization using Cu catalysis in CPME.
• The method offers mild conditions, broad substrate scope, and facile product manipulation.
• The protocol is environmentally friendly due to solvent/catalyst recovery and green solvent usage.
• The selective cross-coupling capability enables its application in complex multistep syntheses.