METHOD FOR PREPARING AVERMECTIN COMPOUND Russian patent published in 2003 - IPC

FIELD: organic chemistry, chemical technology. SUBSTANCE: invention describes method for preparing the avermectin compound of the formula (I) where R¹ is allyl, methylallyl, crotyl, chloroallyl, cinnamyl; R² is hydrogen atom, C_1-4-alkyl or C_1-4-alkoxy group; R³ is C_1-8-alkyl, C_2-8-alkenyl or C_3-8-cycloalkyl; R⁴- is hydrogen, halogen atom, C_1-4-alkyl or C_1-4-alkoxy group. Method involves the following steps: (a) interaction of avermectin derivative B2 with oxidizing agent to yield 5-oxo-compound; (b) interaction of 5-oxo-compound with compound of the formula R¹-O-NH₂ where R¹ means hydrogen atom or hydroxyimino-protective group to yield 5-imino-compound; (c) interaction of 5-imino-compound with agent providing addition of thionocarbonyl group to yield 4'',23-bis-thionocarbonyl ester; (d) interaction of 4'',23-bis-thionocarbonyl ester with deoxygenizing agent to yield 4'', 23-dideoxy-compound; and (e) interaction of 4'', 23-dideoxy-compound with acid to yield compound of the formula (I) and when means allyl then the stage (e) is carried out in the presence of palladium catalyst. EFFECT: improved preparing method, enhanced yield. 11 cl, 2 ex