- New catalytic system Cu(OAc)2-2,4-lutidine-ZnCl2 for olefin cyclopropanation with methyl diazoacetate
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A new efficient catalytic system consisting of Cu(OAc)2, 2,4-lutidine, and ZnCl2 was found for the cyclopropanation of unsaturated compounds with methyl diazoacetate. In the case of conjugated dienes, the process occurs regioselectively at the most alkylated C=C bond.
- Gareev,Sultanova,Biglova,Dokichev,Tomilov
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experimental part
p. 1784 - 1786
(2011/04/23)
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- An efficient and selective conversion of hydrazides into esters and acids
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Hydrazides are selectively oxidised to esters/acids in high yields using Oxone in the presence of an appropriate alcohol/water as a nucleophile at ambient temperature. A variety of functional groups including alkenes, alcohols, ethers, cyclopropyl groups and nitriles are unaffected.
- Srinivas,Subba Reddy,Yadav,Ramalingam
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p. 376 - 377
(2007/10/03)
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- A stereoselective synthesis of methyl trans-3-(2,2-dichloroethenyl)- 2,2-dimethylcyclopropanecarboxylate
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A convenient method is described for the stereoselective synthesis of methyl trans-3-(2,2-dichloroethenyl)-2,2-dimethylcyclopropanecarboxylate (5) via methyl 3,3-dimethyl-4,6,6,6-tetrachlorohexanoate (4) as a key intermediate, which was obtained by addition of carbon tetrachloride to methyl 3,3-dimethyl-4-pentenoate (3). Treatment of (4) with sodium methoxide in a single-vessel via methyl 4,6,6-trichloro-3,3-dimethyl-5-hexenoate (6) gave trans-rich (5) in excellent yield.
- Ma, Jun'an,Huang, Runqiu,Cheng, Junran,Shao, Ruilian,Li, Zaiguo
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p. 1653 - 1659
(2007/10/03)
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- Search for Routes of Synthesis of Permethrin and Chloropermethrin Starting from Halogen-containing Alkenoic Acids
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Promising procedures were developed for the synthesis of permethrin and I-chloropermethrin starting from acid chloride, nitrile, and esters of 3,3-dimethyl-2,2,4,6,6-pentachloro-5-alkenoic acid and 3,3-dimethyl-2,2,6,6-tetrachloro-5-alken-4-olide, which were prepared by adding derivatives of trichloroacetic acid to 1,1-dichloro-4-methyl-1,3-pentadiene in the presence of catalytic amounts of monovalent copper ions and amine.
- Badanyan,Stepanyan,Mikaelyan,Ovivyan,Panosyan
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- TRANSITION-METAL-CATALYSED REACTIONS OF DIAZOESTERS : SYNTHESIS OF CHRYSANTHEMIC AND PERMETHRIC ACID ESTERS BY CYCLOPROPANATION OF CONJUGATED DIENES
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Pyrethroid precursors (permethric and chrysanthemic acid esters) are efficiently synthesized by rhodium(II)-catalysed cyclopropanation of the properly substituted conjugated diene.Reaction selectivities depend on both the catalyst counter-ion and the diazoester alkoxy-group (carbene precursor) and are attributed to non-bonded interactions.
- Demonceau, A.,Noels, A. F.,Anciaux, A. J.,Hubert, A. J.,Teyssie, P.
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p. 949 - 952
(2007/10/02)
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- Pyrethroid Photochemistry: Mechanistic Aspects in Reactions of the (Dihalogenovinyl)cyclopropanecarboxylate Substituent
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The reaction quantum yields of six pyrethroid insecticides in methanol at 300 nm vary 3-10-fold between compounds with a cyclopentanone chromophore (allethrin) as compared with the phenoxybenzyl group (e.g., permethrin, decamethrin)in the alcohol moiety.Chlorine confers greater photostability than bromine in pyrethroids with dihalogenovinyl substituents in the acid moiety.Pathways for photodecomposition of methyl -2,2-dimethyl-3-(2,2-dibromovinyl)cyclopropanecarboxylate in methanol at 250 or 300 nm involve cis-trans isomerization, reductive debromination, and conversion of the dibromovinyl group into a bromomethoxy-epoxide derivative.Isomerization, but not debromination, involves a triplet excited state.
- Ruzo, Luis O.,Casida, John E.
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p. 728 - 732
(2007/10/02)
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