3CR and 4CR Syntheses of highly solvatochromic fluorescent 2-substituted 3-ethynyl quinoxalines

What is it about?

2-Substituted 3-ethynylquinoxalines can be rapidly synthesized in generally excellent yields by a consecutive four-component synthesis starting from electron-rich π-nucleophiles, oxalyl chloride, terminal alkynes, and 1,2-diaminoarenes. The title compounds are highly fluorescent with a pronounced emission solvatochromism. The photophysical properties and electronic structure were additionally corroborated by computations on the DFT level of theory.

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Why is it important?

The Cu-catalyzed Castro coupling of terminal alkynes and in situ generated ynediones followed by cyclocondensation with ortho-phenylene diamines provides an efficient diversity-oriented access to highly emission solvatochromic quinoxalines.