| 摘要 |
The 22,23-dihydro deriv. of Avermectin B1a is made by (a) washing the solids from a bio-fermenter producing such macrolytes with water; (b) extracting with acetone; (c) concentrating to give a crude avermectin ppt. (d) centrifuging the ppt.; (e) dissolving in CHCl3 or CH2Cl2; (f) filtering; (g) drying the filtrate; (h) dissolving in methanol; (i) chromatographing on a hydrophobic resin column equilibrated with 55% methanol in water; (j) washing the resin with 55% methanol in water; (k) eluting with methanol; (l) drying the eluate; (m) dissolving in a mixt. of CHCl3, ethyl acetate, methanol and CH2Cl2; (n) chromatographing on a silica gel column; (o) eluting with the same solvent mixt.; (p) crystallising the eluted fractions of 4-8 deg.C and leaving to stand, to obtain avermectin B1a and B2a with 96% purity; and (q) treating with HI in presence of red phosphorus. It is of use as an insecticide or miticide.
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