Efficient fluoride-catalyzed conversion of CO2 to CO at room temperature

Area of Science:

• Organic Chemistry
• Catalysis
• Green Chemistry

Background:

• Efficient reduction of carbon dioxide (CO2) is crucial for sustainable chemistry.
• Existing methods for CO2 reduction often require harsh conditions or expensive catalysts.
• Selective conversion of CO2 to carbon monoxide (CO) is a key step in many synthetic pathways.

Purpose of the Study:

• To develop an efficient and selective protocol for the reduction of CO2 to CO.
• To explore catalytic systems for CO2 to CO conversion under mild conditions.
• To demonstrate the applicability of this method for isotope labeling in pharmaceutical synthesis.

Main Methods:

• Utilized catalytic cesium fluoride and stoichiometric disilane in DMSO at room temperature for CO2 reduction.
• Employed pressure measurements to monitor CO production.
• Coupled the CO2 reduction with aminocarbonylation using a two-chamber system (COware) for quantification.
• Investigated various disilanes, alternative fluoride sources (KHF2), and silylborane as replacements for disilane.
• Adapted the chemistry for (13)C-isotope labeling using a three-chamber system.

Main Results:

• Achieved rapid reduction of CO2 to CO in 2 hours.
• Demonstrated the system's effectiveness with multiple disilanes, including (Ph2MeSi)2, (PhMe2Si)2, and (Me3Si)3SiH.
• Showed that other fluoride salts (e.g., KHF2) can catalyze the reaction, with KHF2 enabling reactions without an inert atmosphere.
• Confirmed that silylborane maintains high activity, unlike bis(pinacolato)diboron.
• Successfully applied the method for (13)C-isotope labeling of six pharmaceutically relevant compounds.

Conclusions:

• Developed a novel, efficient, and selective protocol for CO2 to CO reduction under mild conditions.
• The protocol is versatile, accommodating various silicon-based reductants and fluoride catalysts.
• The method offers a practical route for CO production and (13)C-isotope labeling for pharmaceutical applications.