Description
N-Ethylbenzisoxazolium Tetrafluoroborate is a peptide-coupling reagent; reacts with a wide range of nucleophiles to give o-hydroxy-N-ethylbenzamido derivatives.
Synthesis
N-Ethylbenzisoxazolium Tetrafluoroborate is prepared by ethylation of benzisoxazole with purified Triethyloxonium Tetrafluoroborate.
storage
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.
Purification Methods
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].
