Catalyst-Controlled Intermolecular Homobenzylic C(sp³)-H Amination for the Synthesis of β-Arylethylamines

Area of Science:

• Organic Chemistry
• Catalysis
• Medicinal Chemistry

Background:

• C-H bond functionalization is crucial for synthesizing complex molecules.
• Selective amination of unactivated C(sp3)-H bonds remains a significant challenge in organic synthesis.

Purpose of the Study:

• To develop a novel catalytic system for selective intermolecular amination of homobenzylic C-H bonds.
• To provide a direct synthetic route to valuable beta-arylethylamines.

Main Methods:

• Utilized a tailored sulfamate as the nitrogen source.
• Employed a C4-symmetrical rhodium(II) tetracarboxylate catalyst.
• Performed regioselectivity studies and computational investigations (activation strain model, energy decomposition analysis).

Main Results:

• Achieved selective intermolecular amination of unactivated homobenzylic C(sp3)-H bonds.
• Demonstrated a broad scope with over 30 examples and high regioselectivity (homobenzylic/benzylic ratio up to 35:1).
• Computational studies revealed a concerted mechanism with an asynchronous transition state, driven by orbital interactions and noncovalent interactions.

Conclusions:

• The developed rhodium-catalyzed reaction offers a direct and efficient access to beta-arylethylamines.
• Regioselectivity is governed by orbital interactions between the rhodium-nitrene and the C-H bond, influenced by noncovalent interactions in the catalytic pocket.
• This methodology holds significant potential for medicinal chemistry applications.