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ChemicalBook CAS DataBase List Cimetidine
51481-61-9

Cimetidine synthesis

1synthesis methods
Cimetidine, 1-cyano-2-methyl-3-[2-[[5-[[methylimidazol-4-yl)methyl]thio] ethyl] guanidine (16.2.5), is synthesized in the following manner. Reacting 2-chloroacetoacetic ether with two moles of formamide gives 4-carbethoxy-5-methylimidazol (16.2.1). Reduction of the carbethoxy group of this produced with sodium in liquid ammonia gives 4- hydroxymethyl-5-methylimidazol (16.2.2). The hydrochloride of the resulting alcohol is reacted with 2-mercaptoethylamine hydrochloride to produce 4-(2-aminomethyl)-thiomethyl- 5-methylimidazol dihydrochloride (16.2.3). This is reacted with N-cyanimido-S,Sdimethyldithiocarbonate to give a thiourea derivative (16.2.4), which upon reaction with methylamine turns into cimetidine (16.2.5).

-

Yield:-

Reaction Conditions:

with potassium carbonate in pyridine;N-methyl-acetamide;

Steps:

7 EXAMPLE 7

EXAMPLE 7 When N-cyano-N',S-dimethylisothiourea is treated with mercuric chloride in pyridine and the mixture added to a mixture of 2-((5-methyl-4-imidazolyl)methylthio)ethylamine and potassium carbonate in dimethylformamide the product is N-cyano-N'-methyl-N"-[2((5-methyl-4-imidazolyl)methylthio)-ethyl]guanidine.

References:

US4049671,1977,A

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