Abstract: The present invention relates to a high-yield method for preparing highly pure (3S,4S)-4-((R)-2-(benzyloxy)tridecyl)-3-hexyl-2-oxetanone using a metal salt of (2S,3S,5R)-2-hexyl-3,5-dihydroxyhexadecanoic acid as an intermediate.

Abstract: Provided is a method of preparing a (6R)-3-hexyl-4-hydroxy-6-undecyl-5,6-dihydropyran-2-one, and a (5R)-2-hexyl-5-hydroxy-3-iminohexadecanoate derivative used in said method as an intermediate.

Abstract: The present invention relates to a high-yield method for preparing highly pure (3S,4S)-4-((R)-2-(benzyloxy)tridecyl)-3-hexyl-2-oxetanone using a metal salt of (2S,3S,5R)-2-hexyl-3,5-dihydroxyhexadecanoic acid as an intermediate.

Abstract: Provided is a method of preparing a (6R)-3-hexyl-4-hydroxy-6-undecyl-5,6-dihydropyran-2-one, and a (5R)-2-hexyl-5-hydroxy-3-iminohexadecanoate derivative used in said method as an intermediate.

Abstract: The present invention relates to a method for preparing clopidogrel 1,5-naphthalenedisulfonate or a hydrate thereof, which comprises reacting a clopidogrel-acid addition salt with disodium 1,5-naphthalenedisulfonate or its hydrate in water, or a mixture of water and an organic solvent. High quality clopidogrel 1,5-naphthalenedisulfonate can be prepared by the inventive method by way of using non-corrosive disodium 1,5-naphthalenedisulfonate.

Abstract: The present invention relates to a method for preparing clopidogrel 1,5-naphthalenedisulfonate or a hydrate thereof, which comprises reacting a clopidogrel-acid addition salt with disodium 1,5-naphthalenedisulfonate or its hydrate in water, or a mixture of water and an organic solvent. High quality clopidogrel 1,5-naphthalenedisulfonate can be prepared by the inventive method by way of using non-corrosive disodium 1,5-naphthalenedisulfonate.

Abstract: Azithromycin is prepared in a high yield by a simple process using a crystalline 9-deoxo-9a-aza-9a-homoerythromycin A hydrate.

Abstract: High purity Form II crystals of clarithromycin can be easily prepared in a high yield by a process comprising the steps of: protecting the 9-oxime hydroxy group of erythromycin A 9-oxime or a salt thereof with a tropyl group and the 2′- and 4″-hydroxy groups with trimethylsilyl groups; reacting 2′,4″-O-bis(trimethylsilyl)erythromycin A 9-O-tropyloxime with a methylating agent; removing the protecting groups and the oxime group of 2′,4″-O-bis(trimethylsilyl)-6-O-methylerythromycin A 9-O-tropyloxime to obtain crude clarithromycin; treating the crude clarithromycin with methanesulfonic acid in a mixture of a water-miscible organic solvent and water to obtain crystalline clarithromycin mesylate trihydrate; and neutralizing the crystalline clarithromycin mesylate trihydrate with aqueous ammonia in a mixture of a water-miscible organic solvent and water.

Abstract: High purity Form II crystals of clarithromycin can be easily prepared in a high yield by a process comprising the steps of: protecting the 9-oxime hydroxy group of erythromycin A 9-oxime or a salt thereof with a tropyl group and the 2′- and 4″-hydroxy groups with trimethylsilyl groups; reacting 2′,4″-O-bis(trimethylsilyl)erythromycin A 9-O-tropyloxime with a methylating agent; removing the protecting groups and the oxime group of 2′,4″-O-bis(trimethylsilyl)-6-O-methylerythromycin A 9-O-tropyloxime to obtain crude clarithromycin; treating the crude clarithromycin with methanesulfonic acid in a mixture of a water-miscible organic solvent and water to obtain crystalline clarithromycin mesylate trihydrate; and neutralizing the crystalline clarithromycin mesylate trihydrate with aqueous ammonia in a mixture of a water-miscible organic solvent and water.