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AssigneeSun Pharmaceutical Industries Limited
InventorsSonny Sebastian, Hetal Virendra Patel, Rajamannar Thennati
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A novel method for the synthesis of piperazine and its derivatives of formula 1, wherein R is selected from hydrogen, or 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, or a methyl group, or a fluoromethyl group; comprising the steps: a. reacting an ester of formula 11 with substituted or unsubstituted ethylenediamine of formula 7 to give 3,4-dehydropiperazine-2-one and its derivatives of formula 12, wherein 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 with a reducing agent to yield the piperazine and its derivatives of formula 1.
A method for the preparation of piperazine and its derivatives of formula 1,
Dependencies are inferred from the claim text.
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Containing only hydrogen and carbon atoms in addition to the ring hetero elements: preparation; Separation; Stabilisation; Use of additives
Not condensed with other rings: having no double bonds between ring members or between ring members and non-ring members
In which the condensed system contains three hetero rings: ortho-condensed systems
Heterocyclic compounds
Term ended 25 Oct 2021 (estimated)
The present invention relates to a novel method for the synthesis of piperazine and its derivatives of formula 1,
wherein R is selected from hydrogen or 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 alkyl having 1 to 6 carbon atoms, a phenylalkyl group the alkyl of which has 1 to 4 carbon atoms; and
Preparation of N-methyl Ethylenediamine of Formula 7 (R=CH3)
To the stirred solution of 40% w/w methylamine (836.6 gms, 10.77 mol) in water, was added 2-chloroethylamine hydrochloride (250.0 gms, 2.155 mol) at room temperature. The reaction mixture was transferred to an autoclave and heated to 100° C. temperature for 6-7 hrs. After completion of the reaction, excess methylamine gas was released and to the mixture was added with stirring solid potassium hydroxide (1.2 kg) at ambient temperature. The organic layer was separated and dried over solid potassium hydroxide (50.0 gms). The dried organic layer was decanted to get crude product which was distilled under vacuum (10-15 mm) at 38°-45° C. to get N-methyl ethylenediamine of formula 7 (69.0 gms, 43.1% yield) as a pale yellow liquid.
Preparation of 1-Methyl-3-phenyl-3,4-dehydropiperazine-2-One of Formula 12 (R=CH3, R1=Phenyl):