Alkynylboration Reaction Leading to Boron-Containing π-Extended cis-Stilbenes as a Highly Tunable Fluorophore

Abstract

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.

Innovative Synthetic Procedures for Luminogens Showing Aggregation‐Induced Emission

“…In addition, another class of unprecedented boron‐containing AIEgens obtained by alkynylboration reactions of alkynamides was reported [78] . The obtained boron‐containing cis ‐stilbenes with extended π‐conjugation show AIEE phenomenon, and thus exhibit great potential as luminophores.…”

Potassium tert‐Butoxide‐Catalyzed Synthesis of α‐Methylene‐β‐Lactams from Propiolamides

“…In the last step, the nitrogen atom's methylation was carried out by the reaction with methyl iodide and sodium hydride in THF according to the procedure reported. [11] Our investigation began with the reaction of N-benzyl-N-methylpropiolamide 1 a (0.25 mmol) with potassium tert-butoxide and dimethylformamide as the solvent. The results of the reaction condition optimization are summarized in Table 1.…”

“…The starting material N ‐benzyl‐ N ‐methyl‐propiolamides 1 , required for this study, was prepared by adding corresponding propionic acids to a solution of 4‐dimethylaminopyridine and dicyclohexylcarbodiimide, followed by the addition of the benzylamines. In the last step, the nitrogen atom‘s methylation was carried out by the reaction with methyl iodide and sodium hydride in THF according to the procedure reported [11] . Our investigation began with the reaction of N ‐benzyl‐ N ‐methyl‐propiolamide 1 a (0.25 mmol) with potassium tert ‐butoxide and dimethylformamide as the solvent.…”

Inter‐Element Boration Reactions of Carbon‐Carbon Multiple Bonds via Lewis‐Basic Activation of Boron Reagents

“…The use of alkynamides instead of propargylic alcohols offered good access to electronically more diverse π‐extended cis ‐stilbenes, including those possessing an electron‐rich aryl group (Scheme 31). [53] The products were highly fluorescent even in the solid state, and their absorption and emission wavelengths are highly tunable depending upon the nature of the substitutent at the acetylenic terminus R 2 . AIEE character was also shown by addition of water to a solution of the product in THF.…”