L-Indanone-2-carboxylate

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. 

Polymer catalysts containing cinchona alkaloids were re-examined by d Angelo for the reaction of l-indanone-2-carboxylate and methyl vinyl ketone, in which the structure of the spacer connecting the base moiety to the Merri-field resin dramatically influenced the enantioselectivity (Scheme 5) [12]. Catalyst 4 (n=7) with a 7-atom-length spacer to quinine exhibits 87% ee, while 4 (n=3) with a 5-atom spacer and 4 ( =9) with an 11-atom spacer gave only 13% and 31% ee, respectively. 

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