Organolithium-Mediated Postfunctionalization of Thiazolo[3,2‑c][1,3,5,2]oxadiazaborinine Fluorescent Dyes

An effective method for transition-metal-free postfunctionalization of thiazolo­[3,2-c]­[1,3,5,2]­oxadiazaborinine dyes via direct lithiation of the 1,3-thiazole ring was developed. The reaction allows valuable regioselective C–H modification of these N,O-chelated organoboron chromophores incorporating different groups, including C-, Hal-, Si-, S-, Se-, and Sn-substituents. As a result, a library of novel fluorescent 1,3-thiazole-based organoboron complexes has been synthesized and characterized. The influence of the donor/acceptor strength of the substituent E on the photophysical properties has been established. The compound with a bulky lipophilic substituent (SnBu3) exhibits a relatively high solid-state photoluminescence quantum yield of 44%.