120298-38-6

The present invention relates to a chiral oxamide of formula (I) useful as an intermediate in the preparation of dorzolamide, and to the preparation thereof. The invention also relates to the preparation of dorzolamide, to the hydrochloride salt thereof, and to the active ingredient contained in a drug useful in the treatment of glaucoma, by means of the intermediate of formula (I).

The present invention relates to a chiral oxamide of formula (I) useful as an intermediate in the preparation of dorzolamide, and to the preparation thereof. The invention also relates to the preparation of dorzolamide, to the hydrochloride salt thereof, and to the active ingredient contained in a drug useful in the treatment of glaucoma, by means of the intermediate of formula (I).

The present invention relates to an improved process for the preparation of (4S,6S)-4- (ethylamino)-5,6-dihydro-6-methyl-4H-thieno[2,3-b]thiopyran-2-sulfonamide-7,7-dioxide hydrochloride ("Dorzolamide hydrochloride") having formula 1. Dorzolamide hydrochloride is prepared by the process of the present invention with high chemical and diastereomeric purity. The present invention also relates to novel intermediate of the formula 20 and a process for its preparation. Dorzolamide hydrochloride is useful in the treatment of ocular hypertension by inhibiting carbonic anhydrase enzyme.

There is provided a process for preparing dorzolamide and processes for preparing intermediates useful in the preparation of dorzolamide. In particular, there is provided a process for preparing an acetoamido sulfone of formula (viii) comprising oxidation of a hydroxysulfonamide of formula (vii) in the presence of an oxidizing agent selected from the group consisting of: a peracid, tert-butyl hydroperoxide, dimethyl dioxirane, selenium dioxide, m-phenanthroline di-N-oxide, nitric acid and hydrogen peroxide. There is also provided a process for preparing an acetoamidosulfone of formula (ix-a) comprising converting a hydroxysulfone of formula (viii) to the acetoamidosulfone of formula (ix-a) in the presence of acetonitrile and an acid. There is also provided a process for separating the cis- and trans-isomers of dorzolamide from a mixture of the trans-isomer of dorzolamide and the cis-isomer of dorzolamide comprising reacting the mixture of isomers with a carboxylic acid.

The present invention relates to one-pot process for the preparation of 6-substituted-4-oxo-thieno[2,3b]thiopyran-2-sulfonic acid of formula (I), which comprises, reacting 2-thienylthiol with alkenyl acid in the presence of an aromatic hydrocarbon solvent and a base, cyclization of the resulting compound and further reacting with an acid anhydride and sulfuric acid to get the desired compound of formula (I). The compound of formula (I) is the key intermediate in the preparation of (S,S)-5,6-dihydro-4-alkyylamino-6-substituted-4H-thieno[2,3-b]thiopyran-2-sulfonamide-7,7-dioxide and analogs thereof.

The present invention relates to an improved process for the preparation of 5,6-dihydro-4-(S)-(ethylamino)-6-(S)methyl-4H-thieno[2,3b]thiopyran-2-sulphonamide-7,7-dioxide hydrochloride of formula (I) commonly known as Dorzolamide Hydrochloride useful as an agent to reduce intraoccular pressure by inhibiting carbonic anhydrase enzyme

The present invention relates to an improved process for the preparation of 5,6-dihydro-4-(S)-(ethylamino)-6-(S)methyl-4H-thieno[2,3b]thiopyran-2-sulphonamide-7,7-dioxide hydrochloride of formula (I) commonly known as Dorzolamide Hydrochloride useful as an agent to reduce intraoccular pressure by inhibiting carbonic anhydrase enzyme.

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