title: Facile Synthesis and Properties of 2-λ(5)-Phosphaquinolines and 2-λ(5)-Phosphaquinolin-2-ones.
abstract: Treatment of 2-ethynylanilines with P(OPh)3 gives either 2,2-diphenoxy-2-λ(5)-phosphaquinolines or 2-phenoxy-2-λ(5)-phosphaquinolin-2-ones under transition-metal-free conditions. This reaction offers access to an underexplored heterocycle, which opens up the study of the fundamental nature of the N=P(V) double bond and its potential for delocalization within a cyclic π-electron system. This heterocycle can serve as a carbostyril mimic, with application as a bioisostere for pharmaceuticals based on the 2-quinolinone scaffold. It also holds promise as a new fluorophore, since initial screening reveals quantum yields upwards of 40%, Stokes shifts of 50-150 nm, and emission wavelengths of 380-540 nm. The phosphaquinolin-2-ones possess one of the strongest solution-state dimerization constants for a D-A system (130 M(-1)) owing to the close proximity of a strong acceptor (P=O) and a strong donor (phosphonamidate N-H), which suggests that they might hold promise as new hydrogen-bonding hosts for optoelectronic sensing.
authors.affiliation: Department of Chemistry & Biochemistry and Materials Science Institute, University of Oregon, Eugene, OR 97403-1253 (USA).
authors.forename: Chris L
authors.initials: CL
authors.lastname: Vonnegut
authors.affiliation: Department of Chemistry & Biochemistry and Materials Science Institute, University of Oregon, Eugene, OR 97403-1253 (USA).
authors.forename: Airlia M
authors.initials: AM
authors.lastname: Shonkwiler
authors.affiliation: Department of Chemistry & Biochemistry and Materials Science Institute, University of Oregon, Eugene, OR 97403-1253 (USA).
authors.forename: Muhammad M
authors.initials: MM
authors.lastname: Khalifa
authors.affiliation: CAMCOR-Center for Advanced Materials Characterization in Oregon, University of Oregon, Eugene, OR 97403-1443 (USA).
authors.forename: Lev N
authors.initials: LN
authors.lastname: Zakharov
authors.affiliation: Department of Chemistry & Biochemistry and Materials Science Institute, University of Oregon, Eugene, OR 97403-1253 (USA). dwj@uoregon.edu.
authors.forename: Darren W
authors.initials: DW
authors.lastname: Johnson
authors.affiliation: Department of Chemistry & Biochemistry and Materials Science Institute, University of Oregon, Eugene, OR 97403-1253 (USA). haley@uoregon.edu.
authors.forename: Michael M
authors.initials: MM
authors.lastname: Haley
mesh_terms: D018360:Crystallography, X-Ray; D008958:Models, Molecular; D015394:Molecular Structure; D011804:Quinolines / Q000138:chemical synthesis* / Q000737:chemistry; D015363:Quinolones / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D011804:Quinolines; D015363:Quinolones
keywords: alkynes; dimerization; fluorescent probes; phosphazenes; phosphorus heterocycles