Cyclopropanecarboxylates reactions

Cyclopentenones reactions of 835, 836 synthesis of 620 Cyclopropanation 648 Cyclopropanecarboxylates, synthesis of 318 Cyclopropanes, synthesis of 772, 773, 785-787... 

Bromocyclopropane has been prepared by the Hunsdiecker reaction by adding silver cyclopropanecarboxylate to bromine in dichlorodifluoromethane at —29° (53% yield) or in tetrachloro-ethane at —20° to —25° (15-20% yield).3 Decomposition of the peroxide of cyclopropanecarboxylic acid in the presence of carbon tetrabromide gave bromocyclopropane in 43% yield.4 An attempt to prepare the bromide via the von Braun reaction was unsuccessful.3... 

It is explosive, and distillation, even under reduced pressure as described, may be dangerous [1], A Hungarian patent describes a safe procedure for in-situ generation of the ester, azeotropic dehydration and subsequent metal-catalysed reaction with 1,3-dienes to give alkyl cyclopropanecarboxylates [2],... 

Reaction of 2,3-dichloroquinoxaline 367 with sodium azide in ethanol has been used to synthesize bistetrazolo-[l,5- 5, l -c]quinoxaline 368 in 65% yield (Scheme 28) <1997JOC4082>. Similarly, reaction of 2,3-dichloroquinoxaline 367 with thiosemicarbazide 366 has been used to generate l,6-diamino-bis-l,2,4-triazolo[4,3- 3,4-f]quinoxaline 365 in 67% yield <2002AP389>. Condensation of cyclopropanecarboxylic acid hydrazide 369 meanwhile gives rise to the cyclopropyl-substituted tetracycle 370 in 93% yield in the presence of l,8-diazabicyclo[5.4.0]undec-7-ene (DBU) as base (Scheme 28) <2005JOC2878>. 

Kinetic studies of the reaction of Z-phenyl cyclopropanecarboxylates (1) with X-benzylamines (2) in acetonitrile at 55 °C have been carried out. The reaction proceeds by a stepwise mechanism in which the rate-determining step is the breakdown of the zwitterionic tetrahedral intermediate, T, with a hydrogen-bonded four-centre type transition state (3). The results of studies of the aminolysis reactions of ethyl Z-phenyl carbonates (4) with benzylamines (2) in acetonitrile at 25 °C were consistent with a four- (5) and a six-centred transition state (6) for the uncatalysed and catalysed path, respectively. The neutral hydrolysis of p-nitrophenyl trifluoroacetate in acetonitrile solvent has been studied by varying the molarities of water from 1.0 to 5.0 at 25 °C. The reaction was found to be third order in water. The kinetic solvent isotope effect was (A h2o/ D2o) = 2.90 0.12. Proton inventories at each molarity of water studied were consistent with an eight-membered cyclic transition state (7) model. 

Schemes. The productive three-step synthesis of bicyclopropylidene (1) utilizing the Kulinkovich reaction of methyl cyclopropanecarboxylate [14]...

Some variations of the method have been used to prepare cyclopropyl and cyclobutyl halides. Simultaneous addition of bromine and 3-bromocyclobutanecarboxylic acid to the suspension of mercuric oxide gives 1,3-dibromocyclobutane in good yield.7 Similarly, cyclopropanecarboxylic acid gives bromo-cyclopropane,9 and 3-(bromomethyl)cyclobutanecarboxylic acid gives 3-(bromomethyl)cyclobutyl bromide.10 In the latter reaction, it was found desirable to remove the water from the reaction as it is formed in order to obtain high yields. Another variation is the addition of a mixture of the acid and mercuric oxide to excess bromine in bromotrichloromethane.6... 

In the following we shall focus on heterogeneous acid-base reactions. One of the best known case studies is the reaction of crystalline benzoic acid with ammonia to form 1 1 ammonium salts [19, 20]. Crystalline p-chlorobenzoic anhydride reacts with gaseous ammonia to give the corresponding amide and ammonium salt [22] a similar reaction has been investigated in the case of optically active cyclopropanecarboxylic acid crystals [23]. 

G. Haufe, T.C. Rosen, O.G.J. Meyer, R. Frohlich, K. Rissanen, Synthesis, reactions and structural features of monofluorinated cyclopropanecarboxylates, J. Fluor. Chem. 114 (2002) 189-198. 

Cyclopropanatioru The ylide I reads with a,/j-unsaturated ketones to form cyclopropanecarboxylic acids in good yield. The reaction with ketones gives glycidic esters 60% yield). 

The cyclopropane ester was prepared by the reaction between 16 g (t)-butyl 2,5-dimethoxy-4-methylcinnamate and dimethylsulfoxonium methylide, prepared as described in the Kaiser reference in the acknowledgements. Hydrolysis of this ester gave 53% trans-2-(2,5-dimethoxy-4-methylphenyl)cyclopropanecarboxylic acid which, after recrystallization from a MeOH/... 

Friedel-Crafts reactionsEthyl cyclopropanecarboxylate undergoes Friedel-( rails reactions with arenes in the presence of A1C13 to form indanones. The proposed reaction mechanism is formulated in the example. 

Aratani, T. (1985) Catalytic asymmetric synthesis of cyclopropanecarboxylic acids an application of chiral copper carbenoid reaction. Pure Appl. Chem., 57, 1839. 

Preparation of 2-Cyclopropylcarbonylamido-5-Chlorobenzophenone To 400.5 g (1.73 mols) of 2-amino-5-chlorobenzophenone dissolved in 220 g (2.18 mols) of triethylamine and 3.5 liters of tetrahydrofuran is added cautiously 181 g (1.73 mols) of cyclopropanecarboxylic acid chloride. The reaction is refluxed 2Vi hours and allowed to cool to room temperature. The solvent is then removed under vacuum to obtain 2-cyclopropylcarbonylamido-5-chlorobenzophenone as a residue which is dissolved in 1 liter of methylene chloride, washed twice with 5% hydrochloric acid, and then twice with 10% potassium hydroxide. The methylene chloride solution is then dried over anhydrous magnesium sulfate, filtered and the solvent removed under vacuum. The residue is recrystallized from 1,500 ml of methanol, charcoaltreating the hot solution to give 356 g of 2-cyclopropylcarbonylamido-5-chlorobenzophenone, MP 105° to 105.5°C (69% yield). 

The 1-ADPM reaction has been used as the key step in the synthesis of a series of cyclopropanecarboxylic acids present in insecticidally-active pyrethrins and pyrethroids [63]. Thus, acetophenone-sensitized irradiation... 

Other cyclopropanecarboxylic acids, present in pyrethroids and of known insecticidal activity, are easily synthesized by the 1-ADPM reaction. Thus, triplet-sensitized irradiation of oxime acetates 74, 76, and 78 affords cyclopropanes 75, 77, and 79, respectively, in good yields. These photoproducts can be transformed to the corresponding carboxylic acids by using conventional routes (Sch. 33) [23]. 

Similarly, 144 has been obtained from the reaction of 1-trimethylsilylcyclopropyl methyl selenide with n-BuLi The a-bromosilane 147 underwent lithiation with n-BuLi in THF at —78 °C to provide 144 with superior efficiency to any other method, Eq. (46))81). 147 was prepared in large quantities by the Hunsdiecker degradation of the 1-trimethylsilylcyclopropanecarboxylic acid 146, obtained by successively reacting the commercially available cyclopropanecarboxylic acid with -BuLi (2 equivalents) and ClSiMe3 82). Uneventfully, 144 added to carbonyl compounds, except for cyclopentanone where enolate anion formation competed the 1-trimethylsilylcyclo-propylcarbinols 148 underwent acid-induced dehydration to the expected 1-trimethyl-silylvinylcyclopropanes 149 79-81) while base induced elimination (KH, diglyme, 90 °C) led to cyclopropylidenecycloalkanes 150 77), Eq. (47). 

With its low yield of 40 % entry 1 is exceptional, since in this case very likely missing steric hindrance causes considerable self condensation diming enolate generation 69). This process has been reported as the exclusive reaction in attempts to deprotonate the unsubstituted ethyl cyclopropanecarboxylate 70). Decreased CH-acidity of the starting material and increased reactivity of the corresponding enolate — both caused by I-strain in the intermediate71) — should be responsible for this self condensation. It proceeds in the deprotonation phase, if not prevented by additional substituents as in almost all other cases in Table 3. 

Preparation of acid chiorides. Cyclopropanecarboxylic acid chloride is prepared according to the reaction... 

Cyclopropanecarboxylic esters. Reaction )f ketene silyl acetals having an allylic hydrogen with a haloform and diethylzinc in pentane results in a cyclopropanecarboxylic ester as the major product. 

Another example of this homoconjugate addition is the reaction of ethyl a-cyano-cyclopropanecarboxylate (4) with 2 eq. of divinylcopperlilhium to give ethyl 2-cyano-5-hexenoate (5) in 70% yield. 

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