In the present aging society, easy-to-use dosage forms for elderly patients, whose swallowing function is often decreased, are in a great demand. It was shown that conventional tablets, capsules, and liquid or syrup preparations were not always easy-to-use dosage forms for elderly patients because of their decreased motor function.1,2) To deal with the demand, great efforts have been made to develop paste preparations and rapidly disintegrating tablets in the oral cavity, using jelly, water-absorbing and swelling gelated materials, or water-soluble polymers.

Direct alpha-vinylations of enolate anions derived from 1,3-dicarbonyl compounds with 4-tert-butyl-1-cyclohexenyl(aryl)iodonium 2 and 1-cyclopentenyl(aryl)iodonium tetrafluoroborates 3 are reported. Frequently, alpha-phenylations compete with the vinylations in the reaction of 1,3-dicarbonyl compounds with alkenyl(phenyl)iodonium salts 2a and 3a. Use of alkenyl(p-methoxyphenyl)iodonium salts 2b and 3b, however, leads to selective alpha-vinylation at the expense of the competing arylation of 1,3-dicarbonyl compounds. Use of an efficient aryl radical trap, 1,1-diphenylethylene, inhibits radical-induced decomposition of the alkenyl(aryl)iodonium salts, thereby improving the yields of alpha-vinylations of enolate anions derived from 1,3-dicarbonyl compounds.

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