Radical Solution to the Alkylation of the Highly Base-Sensitive 1,1-Dichloroacetone. Application to the Synthesis of Z-Alkenoates and E,E-Dienoates

A simple radical-based route to gem-alpha-dichloroketones, relying on the degenerative addition transfer of (S)-[3,3dichloro-2-oxopropyl]-O-ethyl dithiocarbonate (xanthate), is described. The adducts can then be converted into Z-enoates by exposure to Et3N in methanol. In the case of certain substrates, it was possible to form shipped dienoic acid and methyl E,E-dienoates.