β C-H di-halogenation via iterative hydrogen atom transfer.

Area of Science:

• Organic Chemistry
• Synthetic Chemistry
• Radical Chemistry

Background:

• C-H bond functionalization is crucial for organic synthesis.
• Developing selective methods for di-halogenation of sp3 C-H bonds remains challenging.
• Radical relay strategies offer a promising avenue for complex molecule synthesis.

Purpose of the Study:

• To develop a novel radical relay strategy for mono- and di-halogenation of sp3 C-H bonds.
• To achieve the first example of beta C-H di-halogenation.
• To explore the utility of imidate radicals in sequential C-H functionalization.

Main Methods:

• Development of a radical relay strategy involving iterative hydrogen atom transfer (HAT).
• Utilisation of in situ generated imidate radicals for radical translocation.
• Tunable C-X termination for selective halogenation (iodination, bromination, chlorination).

Main Results:

• Successful mono- and di-halogenation of sp3 C-H bonds.
• Demonstration of the first beta C-H di-halogenation via sequential HAT.
• Versatile geminal di-iodide products were synthesized and further elaborated.
• Mechanistic studies revealed the second C-H iodination is twice as fast as the first.

Conclusions:

• The developed radical relay strategy provides a powerful new tool for C-H functionalization.
• The iterative HAT pathway enables selective and efficient di-halogenation.
• The methodology opens new routes for synthesizing complex organic molecules and intermediates.