Cyclopropane carboxylic esters

Despite the toxicity of volatile metal carbonyls, particularly Ni(CO)4, several useful transformations have been developed employing these reagents. Monocarbonylation of gem-dibromocyclopropanes may be accomplished with Ni(CO)4 in the presence of alcohols, amines or (less successfully) thiols, to afford cyclopropane carboxylic esters, amides or thioesters, respectively (equation 202)400. Silylamine or silylsulfide reagents may take the place of amines or thiols401. The intermediacy of a nickel enolate in the carbonylations is... 

Bu3SnLi adds to ,/3-unsaturated esters, and the resulting Li-enolate reacts with 3-methyl-2-butenal to afford 7-hydroxyalkyl tins which are treated with BF3-OEt2 to produce vinyl cyclopropane carboxylic esters (chrysanthemic acid) (Equation (111)).280... 

Bromocyclobutanone acetals (249) are quantitatively converted to cyclopropane-carboxylic esters (250) and alkyl bromides, or to bromoesters in the case of cyclic acetals, upon simple heating in a sealed tube at 200°C (equation 168) . 

Milner, D.J., Spinney, M.A., and Robson, M.J., Preparation of hydroxymethylbenzyl cyclopropane-carboxylate esters as insecticides, Imperial Chemical Industries. Eur. Patent Appl. EP 381317, 1990 Chem. Abstr., 114, 82191, 1991. 

An improved two-step synthesis of cyclopropane-carboxylic ester from y-butyro-lactone makes use of a base-induced elimination ... 

Pyrethroid insecticides are generally classified into one of two large groups on the basis of the central neurotoxic syndrome that they produce [5, 6]. Type I pyrethroids are esters of chrysanthemic acid and an alcohol, having a furan ring and terminal side chain moieties, and absence of a cyano moiety. Allethrin was the first pyrethroid identified in 1949. Allethrin and other pyrethroids such as phenothrin and permethrin with the basic cyclopropane carboxylic ester structure are type I pyrethroids. The insecticidal activity of these synthetic pyrethroids was enhanced further by the addition of a cyano group to give ot-cyano type II pyrethroids such as deltamethrin, fenvalerate, cyfluthrin, cyhalothrin, and lambda-cyhalothrin (Fig. 137.2). 

A remarkably stereospecific elimination has been utilized in the synthesis of ( )-presqualene alcohol and ( )-prephytoene alcohol. The process is based on the addition of the anion derived from a Py-unsaturated phenylsulphone to an aP-unsaturated ester. The intermediate anion (24) cyclizes to give the truns-cyclopropane-carboxylic ester (25), the geometry about the double bond of the unsaturated sulphone... 

The diazo reaction with olefins as shown previously is still the fastest method to get hold of mixtures of diastereomers, often, however, with moderate yields due to the lack of reactivity of the olefins. Several nor-chrysanthemic esters [479], alkoxycyclopro-pane carboxylic esters [480,481], which are interesting because of their photostabihty and insecticidal activity [482], and 2,2,3,3-tetramethylcarboxyhc ester [483] were prepared by this route. Asymmetric synthesis using optically active iron carbonyl-olefin complexes afforded 1-R-configurated esters, i.e. precursors for caronaldehyde [484]. The addition of diazopropane across the double bond of olefinic esters via pyrazolines [485, 486] also provides a rapid access to sometimes more complex cyclopropane carboxylic esters with questionable purity, from which the pure compounds can be separated. 

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 cyclopropane cyclizations by elimination of triflinic acid (CF3S02H) are readily effected by basic treatment of triflones (trifluoromethyl alkyl sulfones) with activated /-protons (equations 46 and 47)39. The cyclopropane diesters 45 are formed on treatment of 44 with potassium hydride in DMSO or sodium methoxide in methanol (equation 48). In contrast, the monoester 46 failed to give the desired cyclopropane40. Addition of carbanions derived from /f, y-unsaturated phenyl sulfones to a, /i-unsaturated carboxylic esters and subsequent elimination of benzenesulfinate ion give cyclopropanes possessing the unsaturated side chain and the ester function in trans positions (equation 49)41. 

This version of the Curtius rearrangement has been applied to the synthesis of amino acid analogs and structures containing amino acids. Several m-2-aminocyclopropane carboxylate esters were prepared by selective hydrolysis of cyclopropane-1,2-dicarboxylates, followed by reaction with DPPA.267... 

Diverging results have been reported for the carbenoid reaction between alkyl diazoacetates and silyl enol ethers 49a-c. Whereas Reissig and coworkers 60) observed successful cyclopropanation with methyl diazoacetate/Cu(acac)2, Le Goaller and Pierre, in a note without experimental details u8), reported the isolation of 4-oxo-carboxylic esters for the copper-catalyzed decomposition of ethyl diazoacetate. According to this communication, both cyclopropane and ring-opened y-keto ester are obtained from 49 c but the cyclopropane suffers ring-opening under the reaction conditions. 

Optical resolution methods with carane-3,4-diol are noteworthy for wide generality. Esters of various cyclopropane carboxylic acids with (1,S, 3A>,4A>,6A>)-carane-3,4-diol were prepared and all (lR)-isomers could easily be obtained by a simple silica gel column chromatography. 

From the point of view of the synthesis of dissonant systems the most important finding reported by Reissig [19c] is the opening of cyclopropanes by fluoride ion-induced desilylation to give carboxylic ester stabilised "homoenolate" anions, from which a series of 4-oxoalkanoic esters (21a ). with a 1,4-D relationship, were prepared (Table 5.6) ... 

Vicinally donor-acceptor-substituted cyclopropanol carboxylic esters have been proven to be versatile synthetic building blocks in organic synthesis [11]. They readily undergo a retroaldol reaction, thus creating a stable enolate that at the same time can be considered as a homoenolate in relation to the newly formed carbonyl function. Shimada et al. applied this strategy to the preparation of y-substituted lactones starting from cyclopropane 21 (Scheme 3) [12]. 

The cyclopropane aldehyde 156 was identified as a versatile chiral building block for the enantioselective synthesis of 4,5 disubstituted y-butyrolactones of type 158 or 159. Both enantiomers of 156 can be easily obtained in a highly diastereo- and enantioselective manner from fixran-2-carboxylic ester 154 using an asymmetric copper-catalyzed cyclopropanation as the key step followed by an ozonolysis of the remaining double bond (Scheme 25) [63]. Addition of... 

Intra- and Intermolecular Kulinkovich Cyclopropanation Reactions of Carboxylic Esters with Olefins. 

Heterosubstituted cyclopropanes can be synthesized from appropriate olefins and car-benes. Since cyclopropane resembles olefins in its reactivity and is thus an electron-rich car bo-cycle (p. 76ft). it forms complexes with Lewis acids, e.g. TiCL, and is thereby destabilized This effect is even more pronounced in cydopropanone ketals. If one of the alcohols forming the ketal is a silanol, the ketal is stable and distillable. The O—Si-bond is cleaved by TiCl4 and a d3-reagent is formed. This reacts with a -reagents, e.g. aldehydes or ketals. Various 4-substituted carboxylic esters are available from 1-alkoxy-l-siloxycyclopropanes in this way (E. Nakamura, 1977). If one starts with l-bromo-2-methoxycyclopropanes, the bromine can be selectively substituted by lithium. Subsequent treatment of this reagent with carbonyl compounds yields (2-methoxycyclopropyl)methanols, which can be transformed to /7,y-unsaturated aldehydes (E.J. Corey, 1975B). 

Dirhodium(II) tetrakis(carboxamides), constructed with chiral 2-pyrroli-done-5-carboxylate esters so that the two nitrogen donor atoms on each rhodium are in a cis arrangement, represent a new class of chiral catalysts with broad applicability to enantioselective metal carbene transformations. Enantiomeric excesses greater than 90% have been achieved in intramolecular cyclopropanation reactions of allyl diazoacetates. In intermolecular cyclopropanation reactions with monosubsti-tuted olefins, the cis-disubstituted cyclopropane is formed with a higher enantiomeric excess than the trans isomer, and for cyclopropenation of 1-alkynes extraordinary selectivity has been achieved. Carbon-hydro-gen insertion reactions of diazoacetate esters that result in substituted y-butyrolactones occur in high yield and with enantiomeric excess as high as 90% with the use of these catalysts. Their design affords stabilization of the intermediate metal carbene and orientation of the carbene substituents for selectivity enhancement. 

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