Reactions of β-Diketones with Aromatic Aldehydes and Ketones in the Presence of Potassium Hydride

Article abstract of DOI:10.1021/jo01294a032

Reaction of benzoylacetone (1a) and acetylacetone (1b) with benzophenone in the presence of excess potassium hydride affords terminal aldol condensation products 5-hydroxy-1,5,5-triphenyl-1,3-pentanedione (3) and 6-hydroxy-6,6-diphenyl-2,4-hexanedione (9), respectively.Potassium hydride promoted reactions of 1a with p-anisaldehyde and p-tolualdehyde result in formation of tetraketones 1,9-diphenyl-5-(p-methoxyphenyl)-1,3,7,9-nonanetetrone (5a) and 1,9-diphenyl-5-(p-tolyl)-1,3,7,9-nonanetetrone (5b), respectively.Evidence is presented to support formation of 5a and 5b via a sequence of reactions involving Michael addition of the dianion of 1a to the monoanion of the unsaturated β-diketones derived from terminal aldol condensation of the respective aldehydes with the dianion of 1a.Reaction of 1b with p-tolualdehyde under similar conditions yields mainly 1,7-bis(p-tolyl)-1,6-heptadiene-3,5-dione (10).Reaction of 1b with the monoanion of 1-phenyl-5-(p-methoxyphenyl)-4-pentene-1,3-dione (2b) in the presence of excess potassium hydride affords the novel hexaketone 1,15-diphenyl-5,11-bis(p-methoxyphenyl)-1,3,7,9,13,15-pentadecanehexone (18).