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Condensation of 2,6-diarylmethylidenecyclohexa(penta)nones with acetylacetone and ethyl acetoacetate

“…In this study in continuation of the previous research in order to refi ne the previous fi ndings [2], to establish the competing reactions, and to increase the yield of the products we repeated the investigation of the reactions between symmetrical dienones I-IV and С-nucleophilic reagents (acetylacetone, ethyl acetoacetate).…”

“…The reaction of dibenzylidenecyclohexanone with acetylacetone and ethyl acetoacetate in the presence of a "soft" cata;yst (piperidine) resulted in the products of carbocyclization, hydroxynaphthalenones, in a preparative yield about 60% [2].…”

“…The specific feature of reactions between 2,6-dibenzylidenecyclohexanone (I) and acetylacetone or ethyl acetoacetate (Scheme 1) consists not in the formation of individual products of carbocyclization, 3-acetyl-8-benzylidene-8а-hydroxy-4-phenyloctahydronaphthalen-2(1Н)-one and ethyl 5-benzylidene-4а-hydroxy-3-oxo-1-phenyldecahydronaphthalen-2-carboxylate (VIа, VIb), as has been erroneously stated in [2], but in the mixture of these compounds with the products of the О-heterocyclization, 1-(8-benzylidene-8а-hydroxy-2-methyl-4-phenyl-4а,5,6,7,8,8а-hexahydro-4Н-chromen-3-yl)ethanone (VIIа), 1-(8-benzylidene-2-hydroxy-2-methyl-4-phenyl-3,4,5,6,7,8-hexahydro-2Н-chromen-3-yl)ethanone (VIIIа), ethyl 8-benzylidene-8а-hydroxy-2-methyl-4-phenyl-4а,5,6,7,8,8а-hexahydro-4Н-chromene-3-carboxylate (VIIb), ethyl 8-benzylidene-2-hydroxy-2-methyl-4-phenyl-3,4,5,6,7,8-hexahydro-2Н-chromene-3-carboxylate (VIIIb) (characterized by spectral data), in overall preparative yields 80-85%. At the use of cyclopentanone II only the products of carbocyclization Vа, Vb formed apparently due to the high carbonyl activity of the cyclopentanone fragment.…”