Benzoylacetone, from acetophenone and acetic anhydride

Benzophenone, directed reaction with acetaldehyde, 50, 68 1,4-Benzoquinone, 2,3-dichloro-5,6-dicyano-, (DDQ), aroma-tization with, 54, 14 Benzoylacetone, from acetophenone and acetic anhydride,... 

Benzophenone, directed reaction with acetaldehyde, 50,68 Benzoylacetone, from acetophenone and acetic anhydride, 51, 93... 

This type of reaction was first used by Dilthey and Fischer69 in connection with the mechanism of the type in Section II, D, 2. By analogy with the well-known formation of benzopyrylium salts from methyl(ene) ketones and o-hydroxybenzaldehyde or o-hydroxy-acetophenone,340 benzoylacetone (84, R = Me, R = H, R" = Ph) and acetophenone (85, RIV = Ph, R" = H) afforded in the presence of acetic anhydride and sulfuric acid, 2-methyl-4,6-diphenylpyrylium sulfoacetate. The interesting feature of this reaction is that a unique product is obtained (i.e., only the carbonyl group of the diketone adjacent to the phenyl enters the condensation, although two such groups are available) R and R" could be reversed, but they are not.69-69 Similarly, dibenzoylmethane (84, R = R" = Ph, R =H) afforded 2,4,6-triphenylpyrylium with acetophenone in 80% yield.69... 

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