δ-C-H Halogenation Reactions Enabled by a Nitrogen-Centered Radical Precursor

Area of Science:

• Organic Chemistry
• Synthetic Methodology
• Radical Chemistry

Background:

• Nitrogen-centered radicals are valuable synthetic intermediates.
• Their generation has historically been challenging, limiting their synthetic utility.
• Existing methods for generating these radicals are often inefficient or lack broad applicability.

Purpose of the Study:

• To develop a novel and efficient precursor for generating nitrogen-centered radicals.
• To demonstrate the application of these radicals in remote C-H functionalization reactions.
• To overcome the limitations associated with the generation of nitrogen-centered radicals in synthesis.

Main Methods:

• Utilized a new hydrazonyl carboxylic acid derivative as a precursor.
• Employed a 1,5-hydrogen atom transfer (HAT) mechanism for radical generation.
• Applied the generated radicals to perform remote C-H fluorination and chlorination of sulfonyl-protected alkyl amines.

Main Results:

• Successfully generated nitrogen-centered radicals from the novel precursor.
• Achieved efficient remote C-H fluorination of alkyl amines.
• Demonstrated effective remote C-H chlorination of alkyl amines.
• The 1,5-HAT process proved effective for these transformations.

Conclusions:

• A new hydrazonyl carboxylic acid precursor enables facile generation of nitrogen-centered radicals.
• This methodology provides a powerful tool for remote C-H fluorination and chlorination.
• The developed strategy broadens the synthetic applications of nitrogen-centered radicals.