Metal-Free Catalyzed Synthesis of Fluorescent Indolizine Derivatives

A mild and high efficient method to prepare indolizines by two-component reaction with the acid as the catalyst was developed. In this reaction, a new ring efficiently formed in one-step reaction. A wide range of substrates could be applied and the desired products were obtained in 8-95% yields under metal-free conditions. Different indolizine derivatives (compounds 3a-3n) were synthesized by general conditions and microwave irradiation conditions, and compound 3a gave the best results with an isolated yield of 95% and 82%, respectively. The structures of synthesized compounds were characterized by spectral analysis, and compound 3m was confirmed by single crystal X-ray analysis. UV-vis absorption and fluorescence properties of these compounds were correlated with substituent groups on indolizine rings.

Automated summary

A mild and efficient method for the synthesis of indolizines using acid as a catalyst in a two-component reaction was developed. The reaction efficiently forms a new ring in one-step, yielding products in a range of 8-95% under metal-free conditions. Substituted indolizine derivatives were synthesized, with compound 3a yielding the best results at 95% and 82% under general and microwave irradiation conditions, respectively. Spectral analysis confirmed the structures of the synthesized compounds, with compound 3m further characterized by single crystal X-ray analysis. UV-vis absorption and fluorescence properties were correlated with substituent groups on the indolizine rings.