Functionally diverse nucleophilic trapping of iminium intermediates generated utilizing visible light

Area of Science:

• Organic Chemistry
• Photocatalysis
• Synthetic Methodology

Background:

• Visible-light photocatalysis has emerged as a powerful tool in organic synthesis.
• Aza-Henry reactions are crucial for forming carbon-nitrogen bonds.
• Previous work highlighted the role of molecular oxygen in catalyst turnover and base generation for nitroalkane additions.

Purpose of the Study:

• To develop improved, mild, and anaerobic conditions for generating iminium ions.
• To enable versatile nucleophilic trapping for diverse functionalization.
• To gain mechanistic insights into the photoredox cycle.

Main Methods:

• Visible-light photocatalysis under anaerobic conditions.
• Generation of iminium ions from tetrahydroisoquinolines.
• Nucleophilic trapping with various nucleophiles.

Main Results:

• Successful generation of iminium ions from tetrahydroisoquinolines under mild, anaerobic conditions.
• Demonstration of versatile nucleophilic trapping, leading to a diverse range of functionalized products.
• Acquisition of mechanistic insights into the underlying photoredox cycle.

Conclusions:

• The developed method offers a mild and efficient route to diverse functionalized tetrahydroisoquinoline derivatives.
• The anaerobic conditions circumvent the need for molecular oxygen, simplifying reaction setups.
• This work expands the scope of visible-light-mediated aza-Henry reactions and provides valuable mechanistic understanding.