反应详情

90 ml of a 30% aqueous solution of monomethylamine is added dropwise with cooling by ice to 4.3 g of N-cyano-N'-[2-((4-methyl-5-imidazolyl)methylthio)ethyl]-O-ethylisourea dissolved in the mixture of 90 ml of ethanol and 60 ml of water. After reaction at 0° C. overnight, the solution is concentrated under reduced pressure and chromatographed similarly as in Example 1 (iii) to separate a reaction solution. Thus obtained solution is concentrated under reduced pressure and is crystallized from isopropyl alcohol-ether to yield 3.0 g of cimetidine, namely N-cyano-N'-methyl-N"-[2-((4-methyl-5-imidazolyl)methylthio)ethyl]guanidine (yield: 75.0%)

1. customAfter reaction at 0° C. overnight
2. concentrationthe solution is concentrated under reduced pressure
3. customto separate a reaction solution
4. concentrationThus obtained solution is concentrated under reduced pressure
5. customis crystallized from isopropyl alcohol-ether