| 摘要 |
PURPOSE: To selectively obtain the subject compound having high insect-repelling activity in high yield by reaction of a specific milbemycin derivative with an organoaluminum reagent having steric hindrance. CONSTITUTION: A milbemycin derivative of formula I (R<1> is methyl, ethyl, isopropyl or sec-butyl; R<2> is a tri-1-4C alkylsilyl or di-6-10C arylmono1-4C alkylsilyl; R<3> is a tri-1-4C alkylsilyl) is reacted with (B) an organoaluminum reagent having steric hindrance of formula II (R<4> -R<7> are each a 1-4C alkyl, a 1-4C alkoxyl or a 6-10C aryl; (n) is 1, 2 or 3) to obtain (C) the objective 15- hydroxymilbemycin derivative of formula III. For example, by using 14,15- epoxy-5-O-(t-butyldimethylsilyl)-7-O-(trimethylsilyl)milbemycin A4 as starting material, 15-hydroxy-5-O-(t-butyldimethylsilyl)-7-O-(trimethylsilyl)-Δ13,14- milbemycin A4 can be obtained.
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