A general carbonyl alkylative amination for tertiary amine synthesis

Area of Science:

• Organic Chemistry
• Synthetic Chemistry

Background:

• Tertiary alkylamines are crucial in pharmaceuticals, agrochemicals, and natural products.
• Carbonyl reductive amination is a primary synthesis method, but lacks direct alkylative variants.
• Existing methods struggle with direct coupling of alkyl fragments to iminium ions.

Purpose of the Study:

• To develop a practical and general synthesis for tertiary alkylamines.
• To achieve a 'carbonyl alkylative amination' through a novel radical-based approach.
• To provide a versatile strategy for complex tertiary amine synthesis.

Main Methods:

• Utilized visible light photoredox catalysis with a silane reducing agent.
• Employed a radical chain process involving alkyl radicals and all-alkyl-iminium ions.
• Coupled aldehydes, secondary amines, and alkyl halides in a metal-free transformation.

Main Results:

• Successfully synthesized diverse tertiary alkylamines via alkyl radical addition to iminium ions.
• Demonstrated a practical, general, and modular synthetic strategy.
• Achieved a metal-free, operationally straightforward transformation without structural constraints.

Conclusions:

• Presented a novel and efficient method for tertiary alkylamine synthesis.
• The radical-based approach overcomes limitations of previous carbonyl alkylative amination strategies.
• This versatile method facilitates the streamlined synthesis of complex tertiary amines.