Hydrogen Peroxide → Lansoprazole

Participants

Reaction Steps

HCl, 1.376 g of 2-mercaptobenzimidazole, and 0.134 g of benzyl triethyl ammonium chloride as an interphase transfer catalyst were mixed in 24 ml of dichloromethane. 0.9534 g of NaOH (40%)/12 ml water mixture solution was dripped into the above mixture while stirring. The temperature of the resulting solution was raised to 40° C. for about 2 hours. Then, dichloromethane was removed from the mixture under a reduced pressure. The solid obtained was stirred with 50 ml of water, and filtered to obtain 3.28 g of solid Lansoprazole precursor: 2-[[3-methyl-4-(2,2,2-trifluoroethoxy)-2-pyridyl]methylthio]-1H-benzimidazole. At room temperature, 3.28 g of the above precursor, 0.1625 g of polyethylene glycol-400 as an interphase transfer catalyst, and 0.3936 g of Mo(acac)2 as an oxidation catalyst were mixed in 45 ml of isopropanol (abbreviated as IPA). To the resulting mixture 3.06 g of 35% H2O2 aqueous solution was added in 5–10 minutes. The reaction was carried out for about one hour, and then 60 ml of water was added, and the reaction was continued for another one hour while stirring. Finally, the precipitate formed was filtered, water washed, and dried to obtain Lansoprazole with a yield of about 88% (HPLC purity>98%).

Provenance & Evidence