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Facile Synthesis and Properties of 2‐λ 5 ‐Phosphaquinolines and 2‐λ 5 ‐Phosphaquinolin‐2‐ones
Author(s) -
Vonnegut Chris L.,
Shonkwiler Airlia M.,
Khalifa Muhammad M.,
Zakharov Lev N.,
Johnson Darren W.,
Haley Michael M.
Publication year - 2015
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201507696
Subject(s) - bioisostere , delocalized electron , chemistry , fluorophore , acceptor , photochemistry , crystallography , fluorescence , physics , organic chemistry , chemical synthesis , quantum mechanics , biochemistry , in vitro
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 NP 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 (PO) and a strong donor (phosphonamidate NH), which suggests that they might hold promise as new hydrogen‐bonding hosts for optoelectronic sensing.