title: One-pot synthesis of fluorescent 2,5-dihydro-1,2,3-triazine derivatives from a cascade rearrangement sequence in the reactions of 1,2,3-triazolium-1-aminide 1,3-dipoles with propiolate esters.
abstract: The reactions of 1,2,3-triazolium-1-aminides 1 (readily available from benzil bishydrazones) with propiolate esters leads to fluorescent 2,5-dihydro-1,2,3-triazine derivatives 2, 3 in one pot. These synthetic reactions can be carried out in acetone, in water, or under solvent-free conditions. The reactions involve a Huisgen cycloaddition followed by a sequence of rearrangements. The final ring-expansion step was blocked by linking a six-methylene hydrocarbon chain between the prospective 1,2,3-triazine C-4 and C-6 atoms, using substrate 8 which gave the fused tricyclic azapropellane product 9 exclusively. X-ray crystal structures were determined for two 2,5-dihydro-1,2,3-triazine derivatives and for compound 9. The UV absorption of the 1,2,3-triazine derivatives showed a dual absorption at ca. 310 and ca. 390 nm with fluorescent emission at ca. 480 and 528 nm (for excitation at 317 nm). The significant Stokes shift of ca. 200 nm shows the potential for biological fluorescent labeling experiments.
authors.affiliation: Chemistry Department and National Centre for Biomedical Engineering Science, National University of Ireland, Galway, Ireland. r.debuitleir@nuigalway.ie
authors.forename: Richard N
authors.initials: RN
authors.lastname: Butler
authors.forename: Aoife M
authors.initials: AM
authors.lastname: Fahy
authors.forename: Anthony
authors.initials: A
authors.lastname: Fox
authors.forename: John C
authors.initials: JC
authors.lastname: Stephens
authors.forename: P
authors.initials: P
authors.lastname: McArdle
authors.forename: D
authors.initials: D
authors.lastname: Cunningham
authors.forename: A
authors.initials: A
authors.lastname: Ryder
mesh_terms: D002384:Catalysis; D018360:Crystallography, X-Ray; D004952:Esters / Q000737:chemistry*; D005453:Fluorescence; D005456:Fluorescent Dyes / Q000138:chemical synthesis* / Q000737:chemistry; D006571:Heterocyclic Compounds / Q000737:chemistry*; D015394:Molecular Structure; D013237:Stereoisomerism; D014227:Triazines / Q000138:chemical synthesis* / Q000737:chemistry*; D014230:Triazoles / Q000737:chemistry*
chemical_list: D004952:Esters; D005456:Fluorescent Dyes; D006571:Heterocyclic Compounds; D014227:Triazines; D014230:Triazoles