Prepn. of 22,23-di:hydro avermectin B1a derivs.

摘要

Method comprises extracting solid component from avermectin fermentation stock with a water-miscible solvent, precipitating the avermectins in an organic solvent and filtering; drying and dissolving in a water-miscible solvent, sepg. the avermectins by column chromatography, crystallising B1a and B2a avermectins and transforming them into the 22,23 dihydro deriv. of Bla(I). X,R1,R2 and R3 are various unspecified radicals.