Patent IE-39102-B1 (IE)
Title: Method for the preparation of piperazine derivatives
IPC: C07D239/48
Filed: 1974-03-25
Abstract: A process for preparing 8-ethyl-5,8-dihydro-5-oxo-2-(1-piperazinyl)pyrido(2,3-d)pyrimidine-6-c arboxylic acids(I) and its pharmaceutically acceptable salts, which comprises hydrolyzing 8-ethyl-5,8-dihydro-5-oxo-2-(1-piperazinyl)pyrido(2,3-d)pyrimidine-6-c arbonitrils(II') oxidizing 6-lower alkanoyl-8-ethyl-5,8-dihydro-5-oxo-2-(1-piperazinyl)pyrido(2,3-d)pyrim idines (II"), and if desired, hydrolyzing the product; or subjecting alkyl 4-(N-substituted ethyl-N-ethyl)amino 2-(1-piperazinyl)-pyrimidine-5-carboxylates(IV) to a Dieckmann reaction, dehydrogenating the resulting 8-ethyl-2-(1-piperazinyl)-5-oxo-5,6,7,8-tetrahydropyrido(2,3-d) pyrimidines (III), then oxidizing or hydrolyzing the resulting 5,8-dihydro-8-ethyl-2-(1-piperazinyl)-5-oxo-pyrido(2,3-d)pyrimidines(II) and if desired, converting the resulting 8-ethyl-5,8-dihydro-5-oxo-2-(1-piperazinyl)pyrido2,3-d) pyrimidine-6-carboxylic acids(II) to a pharmaceutically acceptable salt, and a process for proparing 5,8-dihydro-8-ethyl-2-(1-piperazinyl)-5-oxopyrido(2,3-d)pyrimidines(II), which comprises dehydrogenating 8-ethyl-2-(1-piperazinyl)-5-oxo-5,6.7.8-tetrahydropyrido(2,3-d)pyrimid ines (III), or subjecting alkyl 4-(N-substituted ethyl-N-ethyl)amino-2-(1-piperazinyl)-pyrimidine-5-carboxylates(IV) to a Dieckmann reaction, and dehydrogenating the resulting 8-ethyl-2-(1-piperazinyl)-5-oxo-5,6,7,8-tetrahydropyrido(2,3-d)pyrimid ines(III). The 8-ethyl-5,8-dihydro-5-oxo-2-(1-piperazinyl) pyrido(2,3-d)pyrimidine-6-carboxylic acids (I) and their pharmaceutically acceptable salts are useful as antibacterial agents, and 5 8-dihydro-8-ethyl-2-(1-piperazinyl)-5-oxopyrido(2,3-c)pyrimidines (II) are used as intermediates for producing the 8-ethyl-5,8-dihydro-5-oxo-2-(1-piperazinyl) pyrido(2,3-d)pyrimidine-6-carboxylic acids (I).
A process for preparing 8-ethyl-5,8-dihydro-5-oxo-2-(1-piperazinyl)pyrido(2,3-d)pyrimidine-6-carboxylic acids(I) and its pharmaceutically acceptable salts, which comprises hydrolyzing 8-ethyl-5,8-dihydro-5-oxo-2-(1-piperazinyl)pyrido(2,3-d)pyrimidine-6-carbonitrils(II') oxidizing 6-lower alkanoyl-8-ethyl-5,8-dihydro-5-oxo-2-(1-piperazinyl)pyrido(2,3-d)pyrimidines (II"), and if desired, hydrolyzing the product; or subjecting alkyl 4-(N-substituted ethyl-N-ethyl)amino 2-(1-piperazinyl)-pyrimidine-5-carboxylates(IV) to a Dieckmann reaction, dehydrogenating the resulting 8-ethyl-2-(1-piperazinyl)-5-oxo-5,6,7,8-tetrahydropyrido(2,3-d) pyrimidines (III), then oxidizing or hydrolyzing the resulting 5,8-dihydro-8-ethyl-2-(1-piperazinyl)-5-oxo-pyrido(2,3-d)pyrimidines(II) and if desired, converting the resulting 8-ethyl-5,8-dihydro-5-oxo-2-(1-piperazinyl)pyrido¢2,3-d) pyrimidine-6-carboxylic acids(II) to a pharmaceutically acceptable salt, and a process for proparing 5,8-dihydro-8-ethyl-2-(1-piperazinyl)-5-oxopyrido(2,3-d)pyrimidines(II), which comprises dehydrogenating 8-ethyl-2-(1-piperazinyl)-5-oxo-5,6.7.8-tetrahydropyrido(2,3-d)pyrimidines (III), or subjecting alkyl 4-(N-substituted ethyl-N-ethyl)amino-2-(1-piperazinyl)-pyrimidine-5-carboxylates(IV) to a Dieckmann reaction, and dehydrogenating the resulting 8-ethyl-2-(1-piperazinyl)-5-oxo-5,6,7,8-tetrahydropyrido(2,3-d)pyrimidines(III). The 8-ethyl-5,8-dihydro-5-oxo-2-(1-piperazinyl) pyrido(2,3-d)pyrimidine-6-carboxylic acids (I) and their pharmaceutically acceptable salts are useful as antibacterial agents, and 5 8-dihydro-8-ethyl-2-(1-piperazinyl)-5-oxopyrido(2,3-c)pyrimidines (II) are used as intermediates for producing the 8-ethyl-5,8-dihydro-5-oxo-2-(1-piperazinyl) pyrido(2,3-d)pyrimidine-6-carboxylic acids (I).
[CA1066701A]