Desulfitative Sonogashira cross-coupling of thiopyronin for the synthesis of NIR arylacetylene-containing rhodamines.

A classical, safe and efficient red-shift strategy contributing to NIR arylacetylene-containing rhodamines has been developed via the desulfitative Sonogashira cross-coupling reaction of thiopyronin for the first time, exhibiting a broad substrate scope with good yields. In addition, compound 3m shows great potential for application as a singlet oxygen probe, demonstrating the practicality of the method.