Selective aminoarylation of internal alkynes under transition metal-free conditions provides a sustainable route to fully substituted enamines. However, existing aminoarylation strategies rely on ambiphilic reagents with limited functionality tolerance and are inapplicable to boryl alkynes. Here we report a one-pot process involving alkynone β -trifluoroborates, amines and arynes to construct structurally diverse enaminone-type oxaboracycles in high regio- and stereoselectivity. Incorporation of tetracoordinated boron units and aryl “rotors” at the β -styryl site not only promotes aggregation-induced emission enhancement (AIEE) but also enables wavelength-tunable solid-state emission from violet to red. These oxaboracyclic AIEgens exhibit key advantages as functional luminophores for biological applications, including large Stokes shifts, outstanding chemical and photostability, low cytotoxicity and excellent biocompatibility. Their potential utility is demonstrated by reliable performance as fluorescent probes for live-cell imaging. Mechanistic studies reveal that the proton-dissociated intermediate ( 1a-int1 Z ) serves as the active species in nucleophilic addition to the aryne. Moreover, unique C–H⋯F–B hydrogen-bonding interactions stabilize the E -configured anionic species, accounting for the observed geometric selectivity. A transition metal-free one-pot process involving alkynone β -trifluoroborates, amines and arynes is established to construct structurally diverse boron-containing heterocycles featuring tetrasubstituted enaminone cores in high regio- and stereoselectivity. Incorporation of tetracoordinated boron units and aryl “rotors” at the β -styryl site not only promotes aggregation-induced emission enhancement (AIEE) but also enables wavelength-tunable solid-state emission from violet to red.
Hu et al. (Sun,) studied this question.