Magnesium Methyl Carbonate MMC

When a solution of magnesium methoxide (prepared by the reaction of magnesium with methanol) is saturated with carbon dioxide, an active carboxylating agent, MMC, is produced. The reagent carboxylates substrates capable of enolization apparently by promoting formation of the magnesium chelate of the a-adduct. The reaction has been 

Caution The generation of hydrogen in this preparation necessitates the use of a hood. 

The solution is approximately 2 Af in MMC and remains stable over several months. 

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. 

Cyclohexanone undergoes dicarboxylation when treated with a 10-fold excess of MMC. When 2 g (0.02 mole) of cyclohexanone is treated with 100 ml of approx. 2 M MMC at 120-130° for 6 hours, the usual work-up procedure gives about 50% yield of 2,6-cyclohexanonedicarboxylic acid, mp 123° after recrystallization from ether-petroleum ether. 

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Stile has developed an alternative way to generate magnesium enolate under mild basic conditions . Ketones react with magnesium methyl carbonate (MMC or Stile s reagent)... 

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