Patent ID: 8183391

Claim:
A process for resolving trans racemic (±) (4S,6S, 4R,6R)-4-(Ethylamino)-5,6-dihydro-6-methyl-4H-thieno[2,3-b]thiopyran-2-sulfonamide 7,7-dioxide (dorzolamide trans racemate), of formula (II) comprising a) reacting said racemate with (1S)-(+)-10-camphorsulfonic acid of formula b) obtaining the (4S, 6S) enantiomer by selectively precipitating and isolating (4S,6S) camphorsulfonic acid salt (dorzolamide camphorsulfonate) of formula (III) and c) neutralizing dorzolamide camphorsulfonate of formula (III) to obtain dorzolamide of formula (I)