Sulfonyl Nitrene and Amidyl Radical: Structure and Reactivity

Area of Science:

• Organic Chemistry
• Photocatalysis
• Radical Chemistry

Background:

• Photocatalysis enables control over reactive species like nitrenes and radicals.
• Sulfonyl azides decompose under photocatalysis to generate reactive intermediates.
• These intermediates can drive C-H activation and amide formation.

Purpose of the Study:

• To generate and characterize reactive radicals from sulfonyl azides.
• To investigate the gas-phase reactivity of these radicals in C-H activation.
• To understand mechanisms controlling radical reactivity for synthetic applications.

Main Methods:

• Photocatalytic activation of sulfonyl azides.
• Generation and isolation of sulfonyl nitrene radical anion, sulfonyl nitrene, and sulfonyl amidyl radicals.
• Gas-phase C-H activation experiments.
• Vibrational spectroscopy and DFT calculations for characterization.

Main Results:

• Three distinct radicals were generated: sulfonyl nitrene radical anion, sulfonyl nitrene, and sulfonyl amidyl radical.
• Sulfonyl nitrene radical anion exhibits low reactivity, governed by proton coupled electron transfer.
• Sulfonyl nitrene and sulfonyl amidyl radicals are more reactive, proceeding via hydrogen atom transfer.

Conclusions:

• The reactivity of generated radicals is mechanistically distinct.
• Understanding these mechanisms allows for control over radical reactivity in chemical synthesis.
• This work provides a foundation for utilizing sulfonyl azide-derived radicals in targeted organic transformations.