Stereodivergent Alkyne Reduction by using Water as the Hydrogen Source

Area of Science:

• Organic Chemistry
• Catalysis
• Green Chemistry

Background:

• Alkynes are versatile building blocks in organic synthesis.
• Stereoselective synthesis of alkenes is crucial for various applications.
• Developing sustainable catalytic methods using readily available reagents is a key challenge.

Purpose of the Study:

• To develop a homogeneous palladium-catalyzed method for the stereoselective reduction of alkynes.
• To utilize water (H2O) as a safe and sustainable hydrogen (H2) source.
• To achieve switchable stereoselectivity for both Z and E alkene synthesis.

Main Methods:

• Homogeneous palladium catalysis with rational ligand selection.
• Transfer hydrogenation mediated by a diboron reagent.
• Utilizing water (H2O) as the H2 source and deuterium oxide (D2O) for deuterated products.

Main Results:

• Successful stereodivergent reduction of alkynes to Z and E alkenes with excellent selectivity.
• Demonstrated the utility of simple phosphine ligands for controlling stereochemistry.
• Gram-scale synthesis confirmed the scalability and efficiency of the reaction.
• Mechanistic studies identified key intermediates and pathways.

Conclusions:

• A novel and efficient method for synthesizing Z and E alkenes from alkynes using water as the hydrogen source.
• The catalytic system offers excellent stereocontrol and is amenable to large-scale production.
• This approach provides a greener alternative for alkene synthesis with potential commercial applications.