- Efficient approach to pure entacapone and related compounds
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A new and efficient process through a new intermediate, (2E)-2-cyano-3-(3,4-dihydroxy-5-nirtrophenyl)prop-2-enoic acid 15, has been described for preparing substantially pure entacapone 1. This new intermediate 15 was prepared by Knoevenagel condensation of 3,4-dihydroxy-5-nitrobenzaldehyde 2 with 2-cyanoacetic acid 14 and was further condensed with diethylamine to get pure entacapone 1. Some of the important process-related impurities of entacapone (17, 18, 19, and 20) were also prepared easily from this intermediate 15. Copyright Taylor & Francis Group, LLC.
- Srikanth,Ray, Uttam Kumar,Srinivas Rao,Gupta, P. Badarinadh,Lavanya,Islam, Aminul
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- Process for the preparation of (E)-2-cyano-3-(3, 4-dihydroxy-5-nitrophenyl)-N, N-diethyl-2-propenamide (entacapone)
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The present invention relates to an improved process for the preparation of (E)-N,N-diethyl-2-cyano-3-(3,4-dihydroxy-5-nitrophenyl)acrylamide formula (I) comprising steps of, (a) condensation of 3,4-dihydroxy-5-nitrobenzaldehyde of formula (II) with N,N-diethylcyanoacetamide of formula (III) in the presence of a catalyst and optionally in the presence of phase transfer catalyst in a solvent selected from the group comprising of ethylacetate, acetonitrile, hydrocarbon such as toluene, xylene and like or mixture thereof to give mixture of (E) and (Z)-isomer of N,N-diethyl-2-cyano-3-(3,4-dihydroxy-5-nitrophenyl)acrylamide of formula (IV). b) treating an isomeric mixture of (E) and (Z)-isomer of N,N-diethyl-2-cyano-3-(3,4-dihydroxy-5-nitrophenyl)acrylamide of formula (IV) obtained in step (a) with a halogen in catalytic amounts, in a solvent to give (E)-N,N-diethyl-2-cyano-3-(3,4-dihydroxy-5-nitrophenyl)acrylamide formula (I).
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(2008/06/13)
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