Facile Access to Substituted 1,4-Diaza-2,3-Diborinines

Area of Science:

• Organoboron Chemistry
• Heterocyclic Chemistry
• Synthetic Methodology

Background:

• 1,4-diaza-2,3-diborinines (DADBs) are a class of heterocyclic compounds.
• Exploring new synthetic routes and applications for DADBs is crucial for advancing diborane chemistry.

Purpose of the Study:

• To synthesize novel bis(dimethylamino)-substituted 1,4-diaza-2,3-diborinines (DADBs).
• To convert DADBs into synthetically useful halide derivatives.
• To demonstrate the versatility of the B-X bonds in DADBs for further functionalization.
• To elucidate the mechanism of DADB formation.

Main Methods:

• Synthesis of bis(dimethylamino)-substituted DADBs.
• Conversion of DADBs to halide congeners using HCl or BX3 (X=Br, I).
• Functionalization reactions including salt elimination (MeLi) and commutation (NMe2 DADBs).
• X-ray diffraction analysis of 18 DADB derivatives.
• Mechanistic studies involving transient intermediates.

Main Results:

• Successful synthesis of various DADB derivatives with variable nitrogen substituents.
• Efficient conversion to halide derivatives, showcasing versatile B-X bonds.
• Demonstration of DADB as a general structural motif in diborane(4) chemistry.
• X-ray diffraction revealed strong dependence of bonding parameters on boron substitution.
• Proposed mechanism involving a four-membered azadiboretidine intermediate.

Conclusions:

• The DADB system is a versatile platform for diborane(4) chemistry.
• Halide derivatives of DADBs are valuable synthetic intermediates.
• The formation mechanism involves ring expansion of an azadiboretidine intermediate.
• Structural and synthetic versatility of DADBs is highlighted.