- Modification of the intact retinoid structure in the cyclohexenyl region: Alkylation of methyl 4-oxoretinoate
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Alkylation of methyl 4-oxoretinoate under kinetic-control conditions gives predominantly 3-alkyl-4-oxoretinoates. 3,3-Disubstituted 4-oxoretinoates are obtained similarly from the 3-monosubstituted derivatives, although introduction of the second substituent is more difficult. Evidence has been obtained for a much slower rate of alkylation α to the ester group.
- Shealy,Hosmer,Riordan
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p. 1095 - 1098
(2007/10/02)
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- Base-catalyzed isomerization of retinoic acid. Synthesis and differentiation-inducing activities of 14-alkylated all-trans-, 13-cis-, and 20,14-retro-retinoic acids
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Retinoic acid (1) is isomerized regioselectively by excess amounts of lithium diisopropylamide (LDA) to give 20,14-retro-retinoic acid (3). Alkylation of the intermediate dianion of retinoic acid gave 14-alkylated derivatives of 3. By isomerization of the alkylated retro isomers under basic conditions, several 14-alkyl-all-trans- and -13-cis-retinoic acids were synthesized. The retinoidal activities of these derivatives were examined, based on the ability to induce differentiation of human promyelocytic leukemia cell line HL-60. 20,14-retro-Retinoic acid (3) is 1/50 as active as retinoic acid (1). Although 14-methyl-20,14-retro-retinoic acid (4) is as active as 3, the introduction of a 14-methyl group into all-trans- and 13- cis-retinoic acid resulted in decreased activity. Introduction of bulkier alkyl groups at the C-14 position caused the disappearance of the activity.
- Tanaka,Kagechika,Kawachi,Fukasawa,Hashimoto,Shudo
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p. 567 - 572
(2007/10/02)
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