Enantioselective Hydrothiolation: Diverging Cyclopropenes through Ligand Control

Area of Science:

• Organometallic Chemistry
• Catalysis
• Organic Synthesis

Background:

• Hydrothiolation reactions are crucial for synthesizing sulfur-containing organic compounds.
• Controlling selectivity in metal-catalyzed reactions remains a key challenge in organic synthesis.

Purpose of the Study:

• To develop a versatile rhodium-catalyzed hydrothiolation method using cyclopropenes.
• To investigate the ligand-controlled divergent reactivity of cyclopropenes in hydrothiolation.

Main Methods:

• Employing rhodium catalysis with various bisphosphine ligands.
• Utilizing cyclopropenes as substrates for hydrothiolation reactions.
• Conducting mechanistic studies to elucidate reaction pathways and selectivity origins.

Main Results:

• Achieved divergent synthesis of cyclopropyl sulfides and allylic sulfides from cyclopropenes.
• Demonstrated ligand-dependent control over ring-retention (cyclopropyl sulfides) versus ring-opening (allylic sulfides).
• Identified a common cyclopropyl-Rh(III) intermediate for both pathways, with distinct downstream transformations.

Conclusions:

• The choice of bisphosphine ligand dictates the outcome of Rh-catalyzed hydrothiolation of cyclopropenes.
• Electron-rich Josiphos ligands favor direct reductive elimination yielding enantiomerically enriched cyclopropyl sulfides.
• Atropisomeric ligands promote ring-opening of the intermediate, leading to highly enantio- and regioselective allylic sulfides.