2-Bromo-1-ethylpyridinium tetrafluoroborate

2-Bromo-1-ethylpyridinium Tetrafluoroborate is a carboxyl activation and coupling reagent for peptide synthesis.

2-Bromo-1-ethyl-pyridinium tetrafluoroborate can be used as a coupling reagent for:

• The synthesis of N-methylated peptides in solution and solid phase.
• The synthesis of cyclosporin A fragment and dolastatin 15 pentapeptide moiety.

2-Bromo-1-ethyl-pyridinium tetrafluoroborate is a coupling reagent employed in the synthesis of amides and esters through amidation and esterification reactions, respectively. It is generally prepared by the reaction of triethyloxonium tetrafluoroborate with 2bromo pyridine.

reaction type: Coupling Reactions

Procedure: trifluoroacetic acid (9.2 ml, 12.0 mg molecule) was added to a solution (3.00 g, 12.0 mg molecule) of N-Boc-N-methyl-L-leucine methyl ester (50 ml) at -20C. This mixture was heated to room temperature and stirred for 2 h. The aqueous layer was extracted with CH2Cl2 (2x) over Na2SO4 in order to structure and neutralize the carefully sat. aq. NaHCO3. the aqueous layer was extracted with CH2Cl2 (2x) and said composite organic layer was dried over Na2SO4. After solvent removal in evacuation, the free amine was dissolved in dry CH2Cl2 (50 mL) and N-Cbz-(L)-valine (3.32 g, 13.2 mmol) and DIEA (4.1 mL, 24.0 mmol) were added. Then, a small amount of BEP (3.61 g, 13.2 mmol) was added at room temperature to obtain a yellow solution. It was stirred overnight, diluted with CH2Cl2, and then washed with 1 mol /L aq. KHSO4, sataq . NaHCO3 and brine to wash. The solvent (Na2SO4) was removed after drying and the residue was purified by column chromatography (silica gel, PE:EtOAc 8:2). Dipeptide 1 (4.08 g, 10.4 mmol, 87%) was a colorless resin.