3- Propiolactone enolates

Propiolactone is subject to attack by enolate ions to give propionic acid derivatives of ketones. It may likewise react with nucleophilic enamines to give carboxyethylation according to the reactions. The morpholide is easily hydrolyzed to the corresponding acid. 

The enolate ions of acetoacetic ester and other active methylene compounds react with 0-propiolactone to give the ethoxycarbonyl derivative, but the yields are generally not high. Application of this reaction to 2-ethoxycarbonyldodecanone (equation 53) has been recently patented, with the product reported to be a useful perfume intermediate (77JAP(K)77133952). The reaction is used quite widely with diketene, which gives C-acylation rather than alkylation of the enolate ion, followed by cyclization (72CPB1574). 

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