Process for antiparasitic agent
View Patent ↗An improved process for the preparation of the antiparasitic compound 25-cyclohexyl-22,23-dihydro-5-hydroxyiminoavermectin B1 monosaccharide from doramectine and intermediates therefor and crystalline solvates thereof.
1. A process for the preparation of 25-cyclohexyl-22,23-dihydro-5-oxoavermectin B1 which comprises oxidising 25-cyclohexyl-22,23-dihydroavermectin B1.
wherein said process is performed with manganese dioxide in an organic solvent, wherein the solvent is acetone.
2. Crystalline 25-cyclohexyl-22,23-dihydro-5-hydroxyiminoavermectin B1 toluene solvate obtained by recrystallising 25-cyclohexyl-22,23-dihydro-5-hydroxyiminoavermectin B1 monosaccharide from toluene.
3. Crystalline 25-cyclohexyl-22,23-dihydro-5-hydroxyiminoavermectin B1 monosaccharide methanol and water solvate obtained by crystallising 25-cyclohexyl-22,23-dihydro-5-hydroxyiminoavermectin B1 monosaccharide from aqueous methanol.
4. A process for the preparation of 25-cyclohexyl-22,23-dihydro-5-hydroximinoavermectin B1 monosaccharide which comprises reacting 25-cyclohexyl-22,23-dihydro-5-oxoavermectin B1 with hydroxylamine hydrochloride in aqueous isopropyl alcohol,
wherein the product is crystallised from any of: toluene, methanol, and mixtures thereof.
5. A process for the preparation of 25-cyclohexyl-22,23-dihydro-5-hydroximinoavermectin B1 monosaccharide which comprises reacting 25-cyclohexyl-22,23-dihydro-5-oxoavermectin B1 with hydroxylamine hydrochloride in aqueous isopropyl alcohol,
wherein the process is performed at a temperature of from 40-50° C.,
wherein the product is crystallised from any of toluene, methanol, and mixtures thereof.