N-Ethylbenzisoxazolium Tetrafluoroborate is a peptide-coupling reagent; reacts with a wide range of nucleophiles to give o-hydroxy-N-ethylbenzamido derivatives.
N-Ethylbenzisoxazolium Tetrafluoroborate is prepared by ethylation of benzisoxazole with purified Triethyloxonium Tetrafluoroborate.
The salt is reported not to be hygroscopic, although it etches glass on long exposure to moist air; should be protected from light; reported to be an irritant.
Recrystallise it from MeCN/EtOAc to give magnificent crystals. It is not hygroscopic but on long exposure to moisture it etches glass. It is light-sensitive and should be stored in brown glass bottles. UV (H2O), max 258nm ( 13 100) and 297nm ( 2 900), IR (CH2Cl2): max 1613 (C=N) and 1111-1000 (BF 4 ) [UV, IR, NMR: Kemp & Woodward Tetrahedron 21 3019 1965].
