Alkylation and acylation at a carbon atom

Due to its multiple synthetic uses, alkylation of activated methylene or methine groups should have deserved examination under sonochemical PTC conditions, but the literature does not provide many examples. In addition to the laboratory scale experiments described below, one can mention that a reaction of this type was studied with the purpose of industrial development (p. 254). 

On a benzylic position, deprotonation occurs readily in the presence of aqueous sodium hydroxide, as shown with indene (Eq. 43).a quantitative yield of the alkylated product is obtained. The presence of a PTC is necessary. With respect to the mechanism, it was suggested that alkylation of cyclopentadiene or indene by secondary or tertiary alkyl halides in the presence of potassium hydroxide and Aliquat occurs via a SET process.  

When treated by a solid base in the presence of 18-C-6, thiophene tricarbonyl chromium undergoes a rapid deprotonation and alkylation by, for example, ethyl bromide (Eq. 44). Sonication helps this reaction, which is unfortunately non-selective since the 2-ethyl and the 2,5-diethyl substitution products are present. 

111 Dimens, V.V. Goldberg, Yu. Lukevics, E. Dokl Akad. Nauk SSSR 1988, 298,116-118 Ghent. Abstr. 1989,110, 8270y. 

114 Nefedova, M.N. Liakhovetsky, Yu.L Nekrasov, Yu.S. Izv. Akad. Nauk SSSR, Ser. Khim. 1987,1679 Ghent. Abstr. 1988,109, 37925a. 

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