Method for preparing voriconazole l-camphorsulphonate and voriconazole

A method for preparing voriconazole L-camphorsulfonate, comprising:

• Method 1:
• dissolving a mixture of (2R,3S)/(2S,3R)-2-(2,4-difluorophenyl)-3-(5-fluoropyrimidin-4-yl)-1-(1H-1,2,4-triazol-1-yl)-2-butanol and L-camphorsulfonic acid in a mixed solvent of water and acetone, cooling and crystallizing, and filtering to obtain a crystal of voriconazole L-camphorsulfonate;
• Method 2:
• (a) dissolving a mixture of (2R,3S)/(2S,3R)-2-(2,4-difluorophenyl)-3-(5-fluoropyrimidin-4-yl)-1-(1H-1,2,4-triazol-1-yl)-2-butanol and L-camphorsulfonic acid in a first solvent, crystallizing, and filtering to remove a crystal enriched with L-camphorsulfonate of (2S,3R)-2-(2,4-difluorophenyl)-3-(5-fluoropyrimidin-4-yl)-1-(1H-1,2,4-triazol-1-yl)-2-butanol;
• or
• (a′) dissolving a mixture of L-camphorsulfonate of (2R,3S)/(2S,3R)-2-(2,4-difluorophenyl)-3-(5-fluoropyrimidin-4-yl)-1-(1H-1,2,4-triazol-1-yl)-2-butanol in a first solvent, crystallizing, and filtering to remove a crystal enriched with L-camphorsulfonate of (2S,3R)-2-(2,4-difluorophenyl)-3-(5-fluoropyrimidin-4-yl)-1-(1H-1,2,4-triazol-1-yl)-2-butanol;
• (b) concentrating a filtrate obtained in step (a) or (a′) to dryness to obtain a solid;
• and
• (c) dissolving the solid obtained in step (b) in a second solvent and crystallizing to obtain L-camphorsulfonate of (2R,3S)-2-(2,4-difluorophenyl)-3-(5-fluoropyrimidin-4-yl)-1-(1H-1,2,4-triazol-1-yl)-2-butanol.