Synthesis of 1-Bromosubstituted Analogs of cis-Deltamethrinic and cis-Permethrinic Acids

The diastereoselective synthesis of tetrasubstituted cyclopropanes is described. The two-step procedure is based on the 3-exo-tet Michael addition-initiated ring closure. In the first step, the enolates derived from α,α-dibromoketones react with the α, -unsaturated Fischer alkoxycarbene complexes to [a] 431 Scheme 3. Conversion of cyclopropane 4 to ester 5.[a] The MIRC and demetallation was performed in a one-pot setup.[b] The cyclopropane 5aa was prepared from the tungsten carbene complex 4m.

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Diastereoselective Cyclopropanation through Michael Addition‐Initiated Ring Closure between α,α‐Dibromoketones and α,β‐Unsaturated Fischer Carbene Complexes

Tobrman

Krupička

Polák

et al. 2020

Eur J Org Chem

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Functionalized α-bromocyclopropylmagnesium bromides: Generation and some reactions

2013

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Two-Phase Dibromocyclopropanation of Unsaturated Alcohols Using Flow Chemistry

et al. 2020

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Dibromocyclopropanations are conventionally done by addition of dibromocarbene to alkenes under phase-transfer conditions in batch reactions using a strong base (50% NaOH (aq)), vigorous stirring and long reaction times. We have shown that cyclopropanation of unsaturated alcohols can be done under ambient conditions using continuous flow chemistry with 40% (w/w) NaOH (aq) as the base. The reactions were generally rapid; the yields were comparable to yields reported in the literature for the conventional batch reaction

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Synthesis of 1-Bromosubstituted Analogs of cis-Deltamethrinic and cis-Permethrinic Acids

Abstract: In the synthesis of 1-bromosubstituted analogs of cis-deltamethrinic and cis-permethrinic acids, main components of pyrethroids, the key stage is an intramolecular 1,4-O,C-acyl transfer in reactions of 1-acyloxymethyl-2,2-dibromocyclopropanes with methyllithium.

Cited by 3 publications

References 18 publications

Diastereoselective Cyclopropanation through Michael Addition‐Initiated Ring Closure between α,α‐Dibromoketones and α,β‐Unsaturated Fischer Carbene Complexes

Diastereoselective Cyclopropanation through Michael Addition‐Initiated Ring Closure between α,α‐Dibromoketones and α,β‐Unsaturated Fischer Carbene Complexes

Functionalized α-bromocyclopropylmagnesium bromides: Generation and some reactions

Two-Phase Dibromocyclopropanation of Unsaturated Alcohols Using Flow Chemistry

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