反应详情

N-[[2′-(1-Triphenylmethyltetrazol-5-yl)biphenyl-4-yl]methyl]valine methyl ester (X) is prepared according to the process described in U.S. Pat. No. 5,399,578. N-[[2′-(1-triphenylmethyltetrazol-5-yl)biphenyl-4-yl]methyl]valine methyl ester (X) is reacted with a molar equivalent of oxalic acid or its hydrates selected from oxalic acid dihydrate in an organic solvent selected from alcohols such as ethanol, n-propanol, isopropanol, n-butanol, isobutanol, methylene chloride, ethyl acetate or mixtures thereof, at a temperature of about −20° C. to about 70° C. and the product obtained is isolated by filtration and dried. The product obtained is purified in a solvent selected from chlorinated hydrocarbons such as methylene chloride, chloroform, 1,2-dichloroethane, preferably methylene chloride to produce N-[[2′-(1-triphenylmethyltetrazol-5-yl)biphenyl-4-yl]methyl]valine methyl ester oxalate (Xa) in crystalline form. It has been observed that preparation of oxalic acid salt of Formula (X) results in greater than 98% purity of product by HPLC analysis.

1. customat a temperature of about −20° C. to about 70° C. and the product obtained
2. customis isolated by filtration
3. customdried
4. customThe product obtained
5. customis purified in a solvent