We report the first transition metal-free and trans-selective alkynylboration reaction of alkynes. This unprecedented carboboration reaction is enabled by pseudo-intramolecular activation of alkynylboronates using propargylic alcohols. The carboboration affords 4-alkynyl-1,2-oxaborol-2(5H)-ols, which are not only versatile building blocks but also exhibit strong violet-blue fluorescence emission.

A facile and divergent synthetic process for converting tertiary allylic alcohols to multiply substituted allylic boronates is reported. This methodology is especially effective for tertiary alcohol substrates, providing the corresponding allylic boronates in moderate to good yields.

An unprecedented boron-containing fluorophore, π-extended cis-stilbene, obtained via alkynylboration reaction of alkynamide is reported. Boron-containing πextended cis-stilbenes emit fluorescence with high quantum yields in the solid state and exhibit aggregation-induced emission enhancement. The broad substrate scope of the alkynylboration reaction offers facile access to electronically diverse structures, enabling fine-tuning of light absorption/ emission characteristics. The boron-containing π-extended cisstilbene with a diphenylamino group displays solvatofluorochromism via an intramolecular charge-transfer transition.

A novel access to allylic boronates is described.