Fluorescent Probes from Aromatic Polycyclic Nitrile Oxides: Isoxazoles versus Dihydro‐1λ³,3,2λ⁴‐Oxazaborinines

Abstract

Anthracenenitrile oxide undergoes 1,3‐dipolar cycloaddition reaction with propargyl bromide affording the expected isoxazole as single regioisomer, suitably synthetically elaborated and functionalized with a protected triple bond. The introduction of a bromine atom at the position C10 of the anthracene moiety allows for inserting a variety of aromatic and heterocyclic substituents through Suzuki coupling. A two‐way synthetic route can lead to simple isoxazole derivatives or, after N−O bond reductive cleavage and BF3 complexation, enamino ketone boron complexes. The photophysical properties of both the substituted isoxazoles and the corresponding boron complexes were investigated to show the potentialities for the employment as fluorescent tags in imaging techniques. The quite good quantum yield values confirm the suitability of these compounds in the cellular environment. Scope and limitations of the methodology are discussed.

Scope and Limitations of Boron Fluorescent Complexes from Stable Nitrile Oxides in ABPP Assays

“…Design, synthesis, and application: these aspects must be synchronized and to do that, brand new isoxazole derivatives are currently under preparation by functionalizing the anthryl moiety with several aromatic rings bearing donor and acceptor substituents by means of the Suzuki coupling; moreover, selected heterocycles have been inserted too (Scheme 7). 23…”

Turn-folding in fluorescent anthracene-substituted cyclopenta[d]isoxazoline short peptides

“…Finally, the spectroscopic features of the synthesized turns will be nalized to design proper uorescent tags, for imaging studies at the protein turn points and activity-based protein proling (ABPP) investigations. 31,32…”

Synthesis and Antimicrobial Activity of some Ester Functionalized Isoxazoles incorporating Anthracene Moieties via Nucleophilic Substitution Reaction

“…In an Erlenmeyer flask enfolded with aluminum foil, (1.28mL, 14.32mmol) of propargyl bromide 3 was dissolved in 50 ml of anhydrous dichloromethane, then (3.14g, 14.32mmol) of the afforded nitrile oxide 2 was added slowly. 19 after continues stirring the mixture at room temperature for 2 days, the organic phase was washed with brine (3X100 ml) and dried over anhydrous sodium sulfate. The solvent was evaporated under vacuum and the crude product 4 was purified by column chromatography.…”