| 摘要 |
1. A process for the preparation of 25-cyclohexyl-22,23-dihydro-5-hydroximino-avermectin B1 monosaccharide which comprises reacting 25-cyclohexyl-22,23dihydro-5-oxoavermectin B1 with hydroxylamine hydrochloride in an aqueous organic solvent. 2. A process as claimed in claim 1 wherein the solvent is aqueous isopropyl alcohol. 3. A process as claimed in claim 2 wherein the process is performed at a temperature of from 40-50 degree C. 4. A process as claimed in any one of claims 1 to 3 wherein the product is crystallized from toluene and/or methanol. 5. 25-Cyclohexyl-22,23-d ihydro-5-oxoavermectin B 1. 6. A process for preparing 25-cyclohexyl-22,23-dihydro-5-oxoavermectin B 1 which comprises oxidising 25-cyclohexyl-22,23-dihydroavermectin B1. 7. A process as claimed in claim 6 wherein said process is performed with manganese dioxide in an organic solvent. 8. A process as claimed in claim 7 wherein the solvent is acetone. 9. A process for preparing 25-cyclohexyl-22,23-dihydro-5- hydroxyimino-avermectin B1 monosaccharide from doramectin which comprises the steps of-: (i) catalytic hydrogenation in an organic solvent, (ii) oxidation with manganese dioxide in an organic solvent and, if desired crystallising the product, (iii) reaction with hydroxylamine hydrochloride in an aqueous organic solvent, (iv) optionally recrystallizing the product from toluene or methanol. 10. Crystalline 25-cyclohexyl-22,23-dihydro-5-hydroxyimino avermectin B1 monosaccharide toluene solvate obtained by recrystallising 25-cyclohexyl-22,23dihydro-5-hydroxyiminoavermectin B1 monosaccharide from toluene. 11. Crystalline 25-cyclohexyl-22,23-dihydro-5-hydroxyimino-avermectin B1 monosaccharide methanol/water solvate obtained by crystallising 25-cyclohexyl-22,23-dihydro-5-hydroxyiminoavermectin B1 monosaccharide from aqueous methanol. |
