Carboxylation, of ketones

The carboxylation of ketones is carried out essentially as in the preceding experiment, but at slightly higher temperatures (requiring an oil bath or mantle). Thus, acetophenone (6 g, 0.05 mole) in 100 ml of approx. 2 M MMC is stirred and heated at 110-120° for 1 hour. After cooling, hydrolysis in the acid-ice mixture, and isolation from ether, benzoylacetic acid, mp 99-100°, is obtained in 68% yield. Similarly, 1-indanone gives l-indanone-2-carboxylic acid, mp 100-101°, in 91 % yield. 

Carboxylation of ketones and esters can also be achieved by using the magnesium salt of monomethyl carbonate. 

Kinetic template effects have been postulated in more typical organic aldol condensations, where metals such as lithium and zinc are likely to coordinate both the enolate or enamine nucleophile and the aldehyde in the transition state. The examples shown in Schemes 58184 and 59185 are illustrative of these reactions and the degree of selectivity obtained. The carboxylation of ketones and nitroalkanes by methyl magnesium carbonate to produce P-keto acids and a-nitro acids respectively provides early examples of similar reactions (Scheme 60).186 187 See also Section 61.1.4.4. 

An earlier series of experiments established useful synthetic transformations involving carboxylation of ketones and nitroalkanes to yield P-keto acids and a-nitro acids respectively (Scheme 94).362 363 The reagent is methylmagnesium carbonate and the intermediate (130) can be alkylated with concomitant decarboxylation to provide greater versatility. These reactions can also be extended to ketone functions in imidazoline- and oxazolidine-diones (Scheme 95).364,365... 

C-Carboxylation of enolates.1 Carboxylation of potassium enolates generated from silyl enol ethers is not regioselective because of extensive enolate equilibration. Regiospecific C-carboxylation of lithium enolates is possible with carbonyl sulfide in place of carbon dioxide. The product is isolated as the thiol methyl ester. If simple esters are desired, transesterification can be effected with Hg(OAc)2 (8, 444). Carboxylation of ketones in this way in the presence of NaH and DMSO is not satisfactory because of competing alkylation of the enolate.2 Example ... 

Stiles extended use of the reagent to the tt-carboxylation of ketones to give /I-keto Hclds (3). The Inlermedlute mugneiium lilt (2) uen be ulkviuted In gliu... 

Carboxylation Aluminum chloride. Sodium amalgaoL Sodium phenolate. o-Carboxylation of ketones, nitroalkanes Magnesiom methylcarbonate. 

Inoue et al. have developed photochemical carboxylation of ketones by the virtue of photo-enhanced nucleophilic reactivities of aluminum porphyrin complexes. Treatment of [(TPP)AlNEt2l with aromatic ketones produces the corresponding porphinatoaluminum enolate products,... 

Carboxylation of ketones. In the Robinson-Cornforth1 formal total synthesis of epiandrosterone two relays were utilized. The second was the Koster-Logemann2 ketone (1), available as a by-product of the oxidation of cholesteryl acetate dibromide. Based on model experiments with alicyclic ketones, (1) was converted... 

Ferric etboxide bas also been used for carboxylation of ketones, but yields are not impressive. ... 

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