Ethyl chrysanthemate

Ethyl chrysanthemate (ethyl 2,2-dimethyl-3 c and t -[2-methylpropenyl]-cyclopropane carboxylate) [97-41-6] M 196.3, b 98-102 /llmm, 117-121 /20mm. Purified by vacuum distn. The free trans-acid has m 54° (from, EtOAc) and the free cis-acid has m 113-116° (from EtOAc). The 4-nitrophenyl ester has m 44-45° (from pet ether) [Campbell and Harper J Chem Soc 283 1945 IR Allen et al. JOrg Chem 21 29 1957]. 

The exceptionally high activity of Rh6(CO)16 is exemplified by the 90% yield of ethyl chrysanthemate 11 from 2,5-dimethyl-2,4-hexadiene, even if the ratio EDA/cata-lyst was as high as 200065). When the reactions are carried out in a CO atmosphere, the catalyst can be recovered quantitatively. 

Some care must be taken in drawing conclusions from the E/Z or syn/anti selectivity of a given catalyst/alkene combination. The intrinsic stereoselectivity may be altered in some cases by subsequent isomerizations initiated by the catalyst. For example, epimerization of disubstituted vinylcyclopropanes is effectively catalyzed by palladium compounds the cis - trans rearrangement of ethyl chrysanthemate or of chrysanthemic acid occurs already at room temperature in the presence of PdCl2 L2 (L = MeCN, EtCN, PhCN)96 Oxycyclopropane carboxylic esters undergo metal-... 

Ethyl chrysanthemate (ethyl 2,2-dimethyl-3 c and t -[2-methylpropenyl]-cyclopropane... 

Nishizawa M, Gomi H et al (1993) Purification and some properties of carboxylesterase from Arthrobacter globiformis, stereoselective hydrolysis of ethyl chrysanthemate. Biosci Biotech Biochem 57 594-598... 

C12H20O2 ethyl chrysanthemate 97-41-6 505.75 44.437 2 24705 C12H2202 ethyl 2-isopropyl-5-methylcyclopentanecarbox 116530-99-5 508.57 44.708 2... 

The stereoselective synthesis of ( )-ethyl chrysanthemate (17) has been achieved by Martel and Huyne (1967). The crucial step of their process is the addition of phenyl 3-methyl-2-butenyl sulfone to ethyl-3-methacrylate. 

The carbene derived by metal-catalysed decomposition of ethyl diazoacetate attacks alkenes to introduce a two-carbon fragment into a cyclopropane—an industrial synthesis of ethyl chrysanthemate, a precursor to the pyrethrin insecticides (see p. 1016), uses this reaction. The diene in the starting material is more nucleophilic (has a higher energy HOMO see Chapter 19) than the single alkene in the product, so the reaction can be stopped after one carbene addition. 

Natural Cyclopropanes.—The synthesis of a 2 3 mixture of cis-and tra 5-isomers of racemic ethyl chrysanthemate by addition of ethyl diazoacetate to 2,5-dimethyl-hexa-2,4-diene in the presence of copper powder was first reported in 1924. Aratani et al. have now shown that when the addition is carried out with 1-menthyl diazoacetate in the presence of the chiral (R) copper complex (17), an asymmetric synthesis can be effected leading to a 72 28 mixture of trans-[90% (-l-)-enantiomer] and ci s-[60% (-H )-enantiomer] isomers. Two interesting and new... 

Supported liquid membranes (SLMs) consisting of 5% tri-n-octylphosphine oxide (TOPO) dissolved in di-w-hexylether/n-undecane (1 1) have been used in the simultaneous extraction of a mixture of three stUbene compounds (dienestrol, diethylstilbestrol, and hexestrol) in cow s milk, urine, bovine kidney, and liver tissue matrices [183]. The efficiencies obtained after the enrichment of 1 ng/1 stilbenes in a variety of biological matrices of milk, urine, liver, kidney, and water were 60-70, 71-86, 69-80, 63-74, and 72-93%, respectively. A new method to contribute to the discrimination of polyphenols including resveratrol with synthetic pores was proposed [184]. The work [185] evaluated two types of commonly available chiral detectors for their possible use in chiral method development and screening polarimeters and CD detectors. Linearity, precision, and the limit of detection (LOD) of six compounds (trans-stilbene oxide, ethyl chrysanthemate, propranolol, 1-methyl-2-tetralone, naproxen, and methyl methionine) on four common detectors (three polarimeters and one CD detector) were experimentally determined and the limit of quantitation calculated from the experimental LOD. trans-Stilbene oxide worked well across all the detectors, showing good linearity, precision, and low detection limits. However, the other five compounds proved to be more discriminating and showed that the CD detector performed better as a detector for chiral screens than the polarimeters. 

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