Imidates: an emerging synthon for N-heterocycles

Area of Science:

• Organic Chemistry
• Synthetic Chemistry
• Heterocyclic Chemistry

Background:

• Imidates exhibit unique electronic reactivity, differing from amides.
• They possess both electrophilic and nucleophilic centers, enhancing their utility as organic synthons.
• Imidate motifs are crucial in forming stable 5-membered metallacycles for C-H bond activation.

Purpose of the Study:

• To review the recent applications of imidates in synthesizing N-heterocycles.
• To highlight diverse synthetic methodologies including acid/base catalysis, metal catalysis, and radical-mediated reactions.
• To provide a comprehensive overview of imidate-based C-N annulation reactions.

Main Methods:

• Exploiting the dual electrophilic and nucleophilic nature of imidates.
• Utilizing transition metal coordination to form metallacycles and activate C-H bonds.
• Generating in situ nitrogen radicals for C-N bond formation via 1,5-HAT (Hydrogen Atom Transfer).

Main Results:

• Successful synthesis of diverse N-heterocycles, including oxazolines, oxazines, quinazolines, isoquinolines, imidazoles, and triazoles.
• Demonstration of imidates as effective building blocks for saturated and unsaturated nitrogen-containing ring systems.
• Compilation of various reaction conditions, coupling partners, and imidate substrates.

Conclusions:

• Imidates are highly versatile building blocks for constructing complex N-heterocyclic frameworks.
• The reviewed methodologies offer efficient pathways for synthesizing mono-, bi-, and tricyclic nitrogen-containing compounds.
• This review consolidates recent advancements in imidate-mediated N-heterocycle synthesis.