Cyclopropanecarboxylic acid carbon dioxide

Twenty-four grams (0.11 mole) of red mercuric oxide (Note 1) and 60 ml. of freshly distilled 1,1,2,2-tetrachloroethane are placed in a 250-ml. three-necked flask equipped with a dropping funnel, a reflux condenser, and a stirrer. A solution of 32.2 g. (0.20 mole) of bromine and 17.2 g. (0.20 mole) of cyclopropanecarboxylic acid in SO ml. of tetrachloroethane is added dropwise to the stirred suspension of mercuric oxide over a period of 45 minutes, the flask being kept in a water bath at 30-35° (Note 2). The mixture is stirred after the addition of the reactants until the evolution of carbon dioxide ceases. 

The trapping of lithiohalocyclopropanes by carbon dioxide, aldehydes and acid chlorides, respectively, constitutes a useful route to the corresponding cyclopropanecarboxylic acids, alcohols and ketones. In the case of ketones an intramolecular loss of lithium bromide may take place yielding spiroepoxides which in turn may be isomerized to cyclobutanones. 

Allylmagnesium halides 2 cyclized to cyclopropylmagnesium halides 3 on irradiation of an ethereal solution for one day at 0- 5 C with a high-pressure mercury lamp in a quartz apparatus. Treatment of the irradiated mixture with solid carbon dioxide and subsequent hydrolysis gave cyclopropanecarboxylic acids 4 as the major photo-products, representing 45-75% of the acidic products (absolute yields not given). 

Substitution of a halomercury group attached to a cyclopropane has also been carried out via a cyclopropyl anion. When cii-2-(diisopropylaminocarbonyl)-2-methylcyclopropyltnercury chloride (2) was treated sequentially with an excess of methyllithium or methylmagnesium bromide and then with carbon dioxide, acidic aqueous workup gave, in very good yield, cis-2-(diisopropylaminocarbonyl)-2-methylcyclopropanecarboxylic acid (3a, 74% from 2), which was esterified with diazomethane to give methyl cw-2-(diisopropylaminocarbonyl)-2-methyl-cyclopropanecarboxylate (3b, 90% from 2 when 3a was not isolated). ... 

When treated with a tetraalkylammonium fluoride, various 1-substituted trimethylsilylcyclo-propanes are converted to tetraalkylammonium salts of the corresponding cyclopropyl anions. Such anions are trapped by performing the reaction in the presence of an aldehyde, a ketone or carbon dioxide. The reaction is carried out successfully with electron-donating and electron-withdrawing substituents a to the silyl moiety. The best yield was obtained when methyl 1-trimethylsilylcyclopropanecarboxylate was treated with tetrabutylammonium fluoride in tetra-hydrofuran and acetaldehyde, methyl l-(l-hydroxyethyl)cyclopropanecarboxylate (la) was obtained in 90% yield.Under similar conditions (Z)-2,6-dimethyl-l-[(l-trimethylsilylcy-clopropyl)methylene]cyclohex-2-ene was transformed to (Z)-l- [l-(l-hydroxy-l-methyl-ethyl)cyclopropyl]methylene -2,6-dimethylcyclohex-2-ene (2) in 90% yield in the presence of acetone.Similarly, when carbon dioxide was used as electrophile in the presence of cesium fluoride, typically 1-trimethylsilylcyclopropane-l-carbonitrile was converted quantitatively to 1-cyanocyclopropanecarboxylic acid (3a). ... 

When the substrate was l-methylseleno-l-[(Z)-oct-l-enyl]cyclopropane and the electrophile was 1-bromodecane, l-decyl-l-[(Z)-oct-l-enyl]cyclopropane [(Z)-6b] was obtained in 94% yield if the electrophile was carbon dioxide, l-[(Z>oct-l-enyl]cyclopropanecarboxylic acid [(Z)-7] was obtained in 65% yield. ° However, when the cyclopropyl anion generated in the first step was quenched with an aldehyde, significant amounts of an alkylidenecyclopropane was formed. Thus, when l-methylseleno-l-[(Z)-oct-l-enyl]cyclopropane [(Z)-5] was reacted with butyllithium and then with acetaldehyde a 1 1 mixture of l- l-[(Z)-oct-l-enyl]cyclo-propyljethanol [(Z)-8a] and (2-hexyl-3-hydroxybutylidene)cyclopropane was isolated in 55% combined yield (Table 21). A further example of this type of reaction is available, however no yields were given. 

Carbon dioxide reacts similarly with phosphorane 1 to produce betaine 12, which is converted into the corresponding phosphonium bromide 13 upon protonation with hydrogen bromide, while alkaline hydrolysis affords cyclopropanecarboxylic acid... 

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