Patent ID: 8420846

Claim:
A process for producing (S)-3-[(1-dimethylamino)ethyl]phenyl-N-ethyl-N-methyl-carbamate (rivastigmine) of Formula I or its pharmaceutically acceptable salts, the process comprising: a) reacting a compound of Formula III with a protecting agent of Formula RX in presence of a base and solvent to obtain compound of Formula IV, wherein R is selected from a substituted sulphonyl group and X is a halogen; b) optically resolving the compound of Formula IV employing a resolving agent of compound HA to obtain a compound of Formula V; c) converting the diastereomeric compound of Formula V in presence of a base and a solvent to obtain a compound of Formula VI; d) methylating a compound of the Formula VI using a formylating agent in presence of an organic solvent to obtain a compound of Formula VII; e) deprotecting a compound of the Formula VII in presence of an acid or base to obtain a compound of Formula VIII; f) reacting a compound of Formula VIII with carbamoyl halide in presence of a base in a solvent to obtain rivastigmine of Formula I and further treating the resultant rivastigmine with an optically active acid to obtain a salt thereof.