HBTU is a coupling reagent used in peptide synthesis. HBTU has been shown to effectively suppress racemization.
Synthesis
HBTU is synthesized by reaction of HOBt with TCFH under basic conditions.
Purification Methods
Wash the salt with H2O (3x), CH2Cl2 (3x), dry and recrystallise it from MeCN. Dry it in a vacuum and store it cold in the dark [Dourtoglou et al. Tetrahedron Lett 1269 1978, NMR: Dourtoglou and Gross Synthesis 572 1984]. Benzoxazolinone (2 -hydroxybenzoxazole) [59 -49 -4] M 135.1, m 137 -139o, 142 -143o(corrected), b 121-213o/17mm, 335-337o/760mm. Benzoxazolinone is purified by recrystallisation from aqueous Me2CO followed by distillation at atmospheric pressure, then in a vacuum. The methyl mercury salt recrystallises from aqueous EtOH and has m 156-158o. [Bywater et al. J Am Chem Soc 67 905 1945, Beilstein 27 III/IV 2677.]
