Rhodium-mediated Assembly of New Heterocycles: From Borylenes to Oxaboroles

Area of Science:

• Organometallic Chemistry
• Synthetic Organic Chemistry
• Medicinal Chemistry

Background:

• Rhodium borylene complexes offer unique reactivity for C-B bond formation.
• The development of novel boron-containing heterocycles is crucial for medicinal chemistry.

Purpose of the Study:

• To explore the reactivity of a base-stabilized rhodium borylene complex with alkynes and carbon monoxide.
• To synthesize novel, highly functionalized organic heterocycles with potential therapeutic applications.

Main Methods:

• Reaction of a rhodium borylene complex (κ²-L(CO)Rh(BMes)) with various alkynes (PhC≡C-R).
• Subsequent reaction with carbon monoxide to form cyclic intermediates.
• Release of functionalized oxaborole heterocycles.

Main Results:

• Regioselective addition of alkynes across the boron and CO ligand of the rhodium complex.
• Formation of unique cyclic rhodium complexes (5R).
• Synthesis of diverse oxaboroles (6) from hydroborane, CO, alkyne, and azide.

Conclusions:

• The developed methodology provides access to novel oxaboroles.
• The synthesized oxaboroles share structural similarities with FDA-approved boron-containing drugs.
• This work expands the synthetic utility of rhodium borylene complexes in constructing biologically relevant molecules.