A new cross-conjugated mesomeric betaine

Area of Science:

• Organic Chemistry
• Supramolecular Chemistry
• Computational Chemistry

Background:

• Cross-conjugated mesomeric betaines (CCMBs) are dipolar molecules with charge separation.
• Indolizine reacts with DMAD via [8+2] cycloaddition.
• The reactivity of imidazo[1,2-a]pyridine with DMAD was previously unexplored.

Purpose of the Study:

• To synthesize and characterize the first CCMB isoconjugate derived from imidazo[1,2-a]pyridine.
• To investigate the reaction mechanism and electronic properties of the newly formed CCMB.
• To explore potential charge-transfer complex formation.

Main Methods:

• Reaction of imidazo[1,2-a]pyridine with dimethyl acetylenedicarboxylate (DMAD).
• Structural elucidation using Nuclear Magnetic Resonance (NMR) and High-Resolution Mass Spectrometry (HRMS).
• Computational studies including Density Functional Theory (DFT) and Time-Dependent DFT (TDDFT) calculations.

Main Results:

• Successful synthesis of a novel CCMB isoconjugate.
• NMR and HRMS confirmed the product structure.
• DFT calculations rationalized the reaction pathway, and TDDFT revealed low-lying charge transfer characteristic of CCMBs.

Conclusions:

• Imidazo[1,2-a]pyridine reacts with DMAD to form a new class of CCMB isoconjugates.
• The study provides insights into the formation and electronic properties of these unique dipolar molecules.
• The findings contribute to the understanding of charge-transfer phenomena in organic systems.