Patent ID: 6603003
Filing Date: 2003-08-05
Classification: C07D

Abstract:
A method for the preparation of piperazine and its derivatives of formula 1, wherein R is selected from hydrogen, a lower alkyl group having 1 to 6 carbon atoms or a phenylalkyl group the alkyl of which has 1 to 4 carbon atoms;R1 is selected from hydrogen, a methyl group, a phenyl group optionally substituted with an alkyl group having 1 to 6 carbon atoms, or a phenylalkyl group the alkyl of which has 1 to 4 carbon atoms; and R2 is selected from hydrogen, a methyl group, or a fluoromethyl group; wherein the method comprises the steps: a. reacting an ester of formula 11 with substituted or unsubstituted ethylenediamine of formula 7 to give a 3,4-dehydropiperazine-2-one and its derivatives of formula 12â€ƒwherein R, R1, R2 are as defined above and R6 is a C1 to C4 linear or branched alkyl group; and b. reacting the 3,4-dehydro-piperazine-2-one and its derivatives of formula 12 thus obtained with a reducing agent to yield piperazine and its derivatives of formula 1.