反应详情

温度

-30 °C

A solution of 4.7 mg of 85% metachloroperbenzoic acid and 0.5 ml of fresh methylene chloride is prepared, is placed in a test tube, fitted with a septum and immersed in a dry ice acetone bath. There was added a solution of 0.5 ml of methylene chloride containing 20 mg of avermectin B1a/B1b. The reaction mixture is stirred under nitrogen at -70° C. for two hours and at -30° C. for 30 minutes. Then the reaction mixture was placed in an ice bath for 4 hr. and in a refrigerator for 2 days. The reaction mixture was placed on an 8×8 inch chromatography plate with a layer of 250 microns of silica gel and developed with 5% isopropanol in benzene three times. Two fractions are observed: the faster moving fraction weighing 6.4 mg; a slower moving fraction weighing 8.2 mg. The mass spectral and nuclear magnetic resonance analysis of both fractions indicate that the slow moving fraction was avermectin B 1a/B1b-8,9-epoxide.

1. customis placed in a test tube
2. customfitted with a septum
3. customimmersed in a dry ice acetone bath
4. waitThen the reaction mixture was placed in an ice bath for 4 hr
5. waitand in a refrigerator for 2 days