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2004
Cyclopropane derivatives
Q 0021
Hemisynthesis of Methyl Pyrethroates from γ-Alkoxy-Alkylidene Malonates and
and Isopropylidenetriphenylphosphorane. —
49- 064 Isopropylidenediphenylsulfurane
The hemisynthesis of methyl pyrethroates is achieved via cyclopropanation of alkylidene malonates. γ-Alkoxy-alkylidene malonic acid esters undergo cyclopropanation
with the phosphorane (IVa) and the sulfurane (IVb) with excellent diastereoselectivity.
In contrast, malononitriles react with moderate stereoselectivity, and the cyclopropanation of malonodinitriles proceeds without stereocontrol. In the presence of Me4NOAc
the resulting products undergo decarboxylation to afford a diastereomeric mixture of
monoesters. Acidic cleavage of the dioxolane moiety results in formation of diols
which can smoothly be transformed into pyrethroates. The cis-diol derived from dioxolane (VIII) undergoes lactonization to the derivative (X), a known precursor of deltamethrinic acid. — (KRIEF*, A.; FROIDBISE, A.; Tetrahedron 60 (2004) 35,
7637-7658; Dep. Chem., Fac. Univ. Notre Dame de la Paix, B-5000 Namur, Belg.;
Eng.) — Jannicke
2004
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