Process for the preparation of darunavir
A process for the preparation of Darunavir comprises the reacting of 4-amino-N-(2R, 3S) (3-amino-2-hydroxy-4-phenylbutyl)-N-isobutyl-benzenesulfonamide with (3R, 3aS,6aR)-hexahydrofuro[2,3-b]furan-3-ol derivative in N-methyl-2-pyrrolidinone and isolating the resulting Darunavir. The process yields Darunavir with a very low level of the difuranyl impurity.
1. A process for the preparation of amorphous Darunavir containing less than 0.1% of the difuranyl impurity, comprising coupling the compound of formula 4 with (3R,3aS,6aR)hexahydrofuro [2,3-b]furan-3-ol derivative (5) in N-methyl-2-pyrrolidinone (NMPO)
2. A process for the preparation of amorphous Darunavir containing less than 0.1% of the difuranyl impurity comprising the steps of:
a) coupling the compound of formula 4 with (3R,3aS,6aR)hexahydrofuro[2,3-b]furan-3-ol derivative (5) in N-methyl-2-pyrrolidinone (NMPO) to obtain Darunavir,
b) optionally converting the Darunavir to Darunavir alcohol solvate,
c) dissolving the Darunavir or Darunavir alcohol solvate in a chlorinated organic solvent, and
d) isolating amorphous Darunavir by agitated thin film drying (ATFD).
3. The process according to claim 2 , wherein at least one of the solvents used in step c) is selected from the group consisting of dichloromethane, chloroform, dichloroethane, and mixtures thereof.