Crystalline Diboryldiazomethane: Synthesis and Reactivities

Area of Science:

• Organometallic Chemistry
• Main-Group Chemistry
• Synthetic Organic Chemistry

Background:

• Diboryldiazomethanes are highly desirable but synthetically challenging diazo compounds.
• Dual boryl substitution offers potential for stabilizing and diversifying the diazo carbon center.
• Previous methods have limited access to this important class of compounds.

Purpose of the Study:

• To establish a stable synthetic route to diboryldiazomethanes.
• To investigate the reactivity of diboryldiazomethanes with electrophiles and nucleophiles.
• To explore the potential of diboryldiazomethanes in main-group controlled chemistry.

Main Methods:

• Synthesis of diboryldiazomethanes via N2O-mediated diazo transfer from a preorganized B2N2C scaffold.
• Reactivity studies using Lewis acids to probe binding sites.
• Reactions with methoxide to investigate nucleophilic addition.
• Characterization using multinuclear NMR spectroscopy and single-crystal X-ray diffraction (SC-XRD).

Main Results:

• Successful synthesis of a stable diboryldiazomethane precursor.
• Demonstrated selective binding of Lewis acids to either the terminal nitrogen or carbon center of the diazo unit.
• Observed methoxide-induced B-C bond addition and ring-opening to yield a monoboryl diazo derivative.
• Full characterization of all synthesized species confirmed their structures.

Conclusions:

• This study provides a robust entry point into diboryldiazo chemistry.
• The reactivity of diboryldiazomethanes can be tuned by the nature of the attacking reagent.
• These findings establish a versatile platform for main-group-controlled diazo chemistry.