PHTHALAZONE DERIVATIVES

• Main Authors: MASAO YOSHIDA, RINZO NISHIZAWA, YUKIO TAKEI
• Format: Patent
• Language: English
• Published: 01.09.1983
• Subjects: CHEMISTRY; HETEROCYCLIC COMPOUNDS; METALLURGY; ORGANIC CHEMISTRY

A novel process for producing 7-alkoxycarbonyl-6,8-dimethyl-4-hydroxymethyl-1-phthalazone, and its intermediates. 7-Alkoxycarbonyl-6,8-dimethyl-4-hydroxymethyl-1-phthalazone can be obtained by reacting substituted methylenetriphenylphosphorane with 3,5-dimethyl-4-alkoxycarbonylphthalic anhydride to obtain 6-alkoxycarbonyl-5,7-dimethyl- DELTA 3, alpha -substituted methylenephthalide, reacting the latter with hydrazine to obtain a phthalazone derivative, hydrolyzing the latter, halogenating the hydrolyzate to obtain 7-alkoxycarbonyl-6,8-dimethyl-4-( alpha -halogeno- alpha -substituted methyl)-1-phthalazone and then directly hydrolyzing and decarboxylating the latter or, when said 7-alkoxycarbonyl-6,8-dimethyl-4-( alpha -halogeno- alpha -substituted methyl)-1-phthalazone is 7-alkoxycarbonyl-6,8-dimethyl-1-phthalazone-4- alpha -halogenoacetic acid, reacting it with a carboxylic acid salt such as sodium acetate and simultaneously decarboxylating the acyloxylated compound and then hydrolyzing the decarboxylated product or firstly decarboxylating the 1-phthalazone-4- alpha -halogenoacetic acid derivative, reacting the decarboxylated product with said carboxylic acid salt and then hydrolyzing the reaction product or when said 7-alkoxycarbonyl-6,8-dimethyl-4-( alpha -halogeno- alpha -substituted methyl)-1-phthalazone is 7-alkoxycarbonyl-4-( alpha -carbamoyl- alpha -halogenomethyl)-6,8-dimethyl-1-phthalazone, reacting it with said carboxylic acid salt and then hydrolyzing and decarboxylating the acyloxylated compound simultaneously.