C(sp²)-H functionalization in non-aromatic azomethine-based heterocycles

Area of Science:

• Organic Chemistry
• Heterocyclic Chemistry
• Synthetic Methodology

Background:

• Direct C(sp2)-H functionalization is a rapidly growing area in organic synthesis.
• Non-aromatic azaheterocycles containing azomethine and aldonitrone moieties are important structural motifs.
• Developing efficient methods for functionalizing these moieties is crucial for accessing novel compounds.

Purpose of the Study:

• To provide a comprehensive overview of direct C(sp2)-H functionalization of endocyclic azomethine and aldonitrone groups in non-aromatic azaheterocycles.
• To summarize the progress in this field between 2008 and 2020.
• To highlight the major synthetic routes and their applications.

Main Methods:

• Transition metal-catalyzed cross-coupling reactions.
• Alpha-metalation followed by electrophile quenching.
• (Metal-free) nucleophilic substitution of hydrogen (SNH) reactions.

Main Results:

• Significant advancements have been made in applying these methods to cyclic imines and their derivatives.
• A variety of C-H functionalization strategies have been developed.
• These methods enable direct modification of the azaheterocyclic core.

Conclusions:

• Direct C(sp2)-H functionalization has emerged as a powerful and versatile tool for modifying non-aromatic azaheterocycles.
• The reviewed methodologies offer efficient pathways to complex heterocyclic structures.
• Continued development in this area promises further expansion of synthetic capabilities.