| 摘要 |
PURPOSE:To obtain the titled compound by easy process operation in high yield, industrially and advantageously, by reacting an aminoacetylaldehyde dialkyl acetal with an aqueous salt of S-methylisothiourea and then subjecting the reaction product to ring formation reaction with a specific amount of a strong acid. CONSTITUTION:An aminoacetylaldehyde dialkyl acetal shown by formula I is reacted with an aqueous salt of S-methylisothiourea such as sulfate in a water medium at reflux temperature for 1-3hr to form an N-(2,2-dialkoxyethyl) guanidine salt shown by formula III (first process), preferably not isolated, 1mol. of the reaction product is subjected to ring formation reaction in the presence of 0.005-0.5 equivalent strong acid such as sulfuric acid or hydrochloride acid at reflux temperature for 1-3hr (second process) to give the aimed compound shown by formula IV useful as an intermediate for drugs. Since the reactions including isolating and purifying process can be carried out only in the aqueous system throughout the first and the second processes, this method has merits of no danger in handling organic solvents.
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