| 摘要 |
A method is disclosed for preparing pyrylium and thiapyrylium salts having the formula represented below (where X is O,S or Se): <IMAGE> and where R1 and R2 represents a branched or unbranched alkyl radical having up to about 15 carbon atoms, an aromatic group having as substituents alkyl radicals with 1 to about 15 carbon atoms, alkoxy radicals having 1 to about 4 carbon atoms, substituted amino radicals have 1 to 2 carbon radicals containing 1 to about 4 carbon atoms, a heterocyclic group having as substitute alkyl radicals with 1 to about 15 carbon atoms, alkoxy radicals having 1 to about 4 carbon atoms and amino radicals having 1 or 2 carbon radicals containing 1 to about 4 carbons, thiophene radicals and furan radical containing a variety of substituents; R3 represents a thioalkyl radical having 1 to about 4 carbon atoms thiobenzyl, thioaryl and thiocycloalkyl, as well as thiohetaryl radicals such as thiohydridyl and related 5-and 6-membered systems; and Z- is an anionic function. The salts are prepared by condensing the methyl ketone with carbon disulfide in the presence of sodium hydride, treating the product with methyl iodide to form the alpha -oxoketenedithioacetal; condensing the alpha -oxoketenedithioacetal with another methyl ketone in the presence of two equivalents of potassium tert-butoxide to form a 1,5-enedione; and cyclizing the enedione with tetrafluoroboric acid.
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