Butyl chloroformate → HCID 90904970, compound

Participants

Reaction Steps

tert-butyl[2-(2-tert-butoxycarbonylamino-ethylsulfanyl)-benzoimidazol-1-yl]-acetate (Precursor V-02b) is dissolved in 3M HCl in AcOEt and stirred for 1 h at rt. Evaporation of the solvent in vacuo yields 2-(1-tert-butoxycarbonylmethyl-1H-benzoimidazol-2-ylsulfanyl)-ethyl-ammonium chloride as a colourless solid. To a solution of n-butylchloroformate (14.9 mg, 14 μl, 0.11 mmol) in dry THF (0.5 ml) cooled to 0° C. is added a solution of HOBt (17.3 mg, 0.11 mmol) and DIPEA (18 mg, 23.8 μl, 0.14 mmol) in dry THF (0.5 ml). The resulting mixture is stirred for 10 min. It is then added dropwise at 0° C. onto a solution of 2-(1-tert-butoxycarbonylmethyl-1H-benzoimidazol-2-ylsulfanyl)-ethyl-ammonium chloride (30 mg, 0.09 mmol) and DIPEA (11.2 mg, 14.9 μl, 0.09 mmol) in dry THF (0.7 ml). The resulting mixture is stirred for 1 h at rt. Then tris-(2-aminoethyl)amine polystyrene (3.4 mmol/g, 25.6 mg) is added and the resulting slurry is allowed to stir for 2 h at rt and then filtered. The solvent is removed in vacuo and the residue is diluted with dichloromethane (5 ml). This organic phase is washed once with a saturated aqueous NaHCO3 solution and a saturated aqueous KH2PO4 solution. Evaporation of the solvent in vacuo yields the title compound (17.1 mg) in 48% as a colourless oil: tR=2.35 min (LC-2), ESI-MS (pos.): m/z 408.29 [M+H]+.

Provenance & Evidence