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AssigneeCipla Limited
InventorsManjinder Singh Phull, Rajendra Narayanrao Kankan, Dharmaraj Ramachandra Rao, Ashwini Amol Sawant, Sanoj Thoppil
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The present invention provides a process for preparing methyl 5-acetamido-4-amino-6-(1,2,3-triacetoxypropyl)-5,6-dihydro-4H-pyran-2-carboxylate (V), which process comprises reducing methyl 5-acetamido-4-azido-6-(1,2,3-triacetoxypropyl)-5,6-dihydro-4H-pyran-2-carboxylate (IV) in the presence of a reducing agent selected from the group consisting of lithium aluminium hydride, sodium borohydride, zinc/ammonium chloride, zinc-ferric chloride and ferric chloride/sodium iodide. The present invention also provides compounds of formula (VIII) and (IX) which may be used in the synthesis of zanamivir. The present invention also provides processes for preparing compounds (VIII) and (IX) and processes involving their use, including in the synthesis of zanamivir.
The process according to claim 3, wherein the methyl 5-acetamido-4-amino-6-(1,2,3-triacetoxypropyl)-5,6-dihydro-4H-pyran-2-carboxylate (V) is prepared by reducing methyl 5-acetamido-4-azido-6-(1,2,3-triacetoxypropyl)-5,6-dihydro-4H-pyran-2-carboxylate (IV) in the presence of a reducing agent selected from the group consisting of lithium aluminium hydride, sodium borohydride, zinc/ammonium chloride, zinc-ferric chloride and ferric chloride/sodium iodide.
A process for preparing the compound of formula (VIII) according to claim 15, which process comprises reacting a compound of formula (V) with a cyanogen halide of formula N≡C—X, wherein X is fluoro, chloro, bromo or iodo.
A process for preparing the compound of formula (IX) according to claim 16 which process comprises deacetylation of a compound of formula (VIII) in the presence of a deacetylating agent.
A process for preparing a compound of formula (VII), which process comprises hydrolysing the compound of formula (IX) according to claim 16.
Methyl 5-acetamido-4-cyanamido-6-(1,2,3-triacetoxypropyl)-5,6-dihydro-4H-pyran-2-carboxylate of formula (VIII).
Methyl 5-acetamido-4-cyanamido-6-(1,2,3-trihydroxypropyl)-5,6-dihydro-4H-pyran-2-carboxylate of formula (IX).
Zanamivir having purity greater than or equal to 99.5% and having the following structure:
20-22. (canceled)
Dependencies are inferred from the claim text.