Retinylidene dimedone

C6 all-frflrt5-Retinylidene dimedone [70424-15-6] (all- )-2-[3,7-Dimethyl-9-(2,6,6-trimethyl-1-cyclohexen-1 -yl)-2,4,6,8-nonatetraenylidene]-5,5-dimethyl-l, 3-cyclohexanedione... 

Axerophthene (A7) Retinyl acetate (A3) Retinyl methyl ether (All) N-(4-HydroxyphenyOretinamide (E16) N-(4-Hydroxypheny 1)-13-ci.s-retinamide (E21) 13-c/i-Retinoic acid (E6) Retinyl butyl ether N-EthylKtinamide (Ell) iV-(2-Hydroxyethyl)retinamide (E12) )V-(4-Pivaloyloxyphenyl)retinamide A -(4-Propionoxyphenyl)retinamide Retinylidene dimedone (C6) Retinylidene acetylacetone (C4) Etretinate (FI) Motretinid (F3) TMMP" analog of retinyl methyl ether... 

Condensation of a retinaldehyde with a 1,3-diketone under Knoevenagel conditions in the presence of piperidinium acetate gave a retinylidene 1,3-diketone. Thus, for example, (607) was formed from retinaldehyde (2) and dimedone (606) (Acton and Brossi, 1980b Acton et aL, 1980). 

Condensation of this mixture with dimedone and acetylacetone produced reti-nylidene-ll- H dimedone (LIX) and retinylidene-ll- H acetylacetone (LVIII), respectively, as only the all-trans isomer because the 13-c/5-retinaldehyde is isomerized to the all-trans isomer under the reaction conditions used (Fig. 15) (Acton and Brossi, 1980). 

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