- Synthesis of S-(+)-methoprene
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An optically active juvenile hormone analogue, S-(+)-methoprene (1), is synthesized in six steps from technical grade S-(+)-3,7-dimethyl-1,6-octadiene (''(+)-dihydromyrcene'', e.e. ca. 50percent) by a novel procedure which begins with selective hydroalumination-oxidation to give S-(-)-citronellol.This alcohol is oxidized to give S-(-)-citronellal which on reaction with allylmagnesium chloride affords 6S,10-dimethyl-1,9-undecadien-4R/S-ol (5).Smidt-Moiseev oxygenation of 5 followed by dehydration leads to 6S,10-dimethyl-3E,9-undecadien-2-one.The latter on treatment with isopropoxyethynylmagnesium bromide is transformed into isopropyl 3,7S,11-trimethyl-2E/Z,4E,10-dodecatrienoate which upon Brown solvomercuration-reduction in MeOH gives 1 in 14percent overall yield.
- Odinokov, V. N.,Ishmuratov, G. Yu.,Kharisov, R. Ya.,Serebryakov, E. P.,Tolstikov, G. A.
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- TERPENES IN ORGANIC SYNTHESIS. 13. SYNTHESIS OF S-(+)-METHOPRENE FROM (+)-&β-CITRONELLENE
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S-(+)-Methoprene (I) was synthesized from (+)-β-citronellene (III) with an optical purity of about 50percent.The optical purity of the key intermediate, S-(-)-7-methoxy-3,7-dimethyl-1-octanol (IV), can be increased by fractional crystallization of the optical active acid phthalate salt (VI) followed by hydrolytic crystallization of the alcohol (IV).The yield of (I) at the final synthetic stage can be increased by use of interphase catalysis.S-(+)-Methoprene has a higher morphogenetic activity than the racemic form.
- Serebryakov, E. P.,Zhdankina, G. M.,Kryshtal', G. V.,Mavrov, M. V.,Khao, Nguen Kong
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p. 739 - 743
(2007/10/02)
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