Ruthenium-Catalyzed Asymmetric N-Acyl Nitrene Transfer Reaction: Imidation of Sulfide

Area of Science:

• Organic Chemistry
• Catalysis
• Asymmetric Synthesis

Background:

• Asymmetric nitrene transfer reactions are valuable for creating nitrogen functional groups.
• Transferring N-acyl amides via nitrene intermediates is challenging due to side reactions like dimerization and Curtius rearrangement.

Purpose of the Study:

• To develop a highly enantioselective method for imidation of sulfides using N-acyl nitrene transfer.
• To overcome the limitations associated with N-acyl nitrene intermediates in catalytic reactions.

Main Methods:

• Utilized a (OC)ruthenium-salen complex (2b) as a catalyst.
• Employed 3-substituted 1,4,2-dioxazol-5-ones (1) as the N-acyl nitrene source.
• Investigated the catalytic decomposition of dioxazolones and subsequent nitrene transfer to sulfides.

Main Results:

• Achieved highly enantioselective imidation of sulfides.
• Demonstrated efficient catalytic N-acyl nitrene transfer without external activation (heating or UV).
• Obtained good to excellent enantioselectivities, reaching up to 98% ee, with no diazene or isocyanate contamination.

Conclusions:

• The developed ruthenium-catalyzed N-acyl nitrene transfer is an effective strategy for enantioselective sulfide imidation.
• This method provides a robust solution for previously difficult N-acyl amide synthesis.
• The catalytic system offers a mild and efficient route to chiral sulfur-nitrogen compounds.