- Macrocyclic Hydrocarbons with Rigid and Flexible Building Blocks
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We report the synthesis of a series of new hydrocarbon macrocycles. Following the dithia-phane route, four large rings 3-6 of the cyclophane type containing different numbers of ring atoms were prepared confirming the general applicability of this route compared to alternative macrocyclizations. Cycle 3 is the hydrocarbon analogue to the tetralactam and the sulfone amide macrocycles 1 and 2 used in many rotaxane syntheses. The macrocycles synthesized here are supposed to be uselful as wheels in the slipping approach to rotaxanes to further establish a reference system for the cavity size of cyclic compounds by comparing them to certain complemenatry blocking groups. The x-ray data obtained of the macrocycles 3, 5, and 6 reveal the cavity shape and size in solid state.
- Windisch,Voì?gtle,Nieger,Lahtinen,Rissanen
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p. 642 - 653
(2007/10/03)
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- Synthesis and structure-activity relationships of stilbene retinoid analogs substituted with heteroaromatic carboxylic acids
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Retinoids elicit biological responses by activating a series of nuclear receptors. Six retinoid receptors belonging to two families are currently known: retinoic acid receptors (RAR(α,β,andγ)) and retinoid X receptors (RXR(α,β,andγ)). Stilbene retinoid an
- Beard,Chandraratna,Colon,Gillett,Henry,Marler,Song,Denys,Garst,Arefieg,Klein,Gil,Wheeler,Kochhar,Davies
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p. 2820 - 2829
(2007/10/02)
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- Conformationally Restricted Retinoids
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A series of conformationally restricted retinoids was synthesized and screened in two assays used to measure the ability of retinoids to control cell differentiation, namely, the reversal of keratinization in tracheal organ culture from vitamin A deficient hamsters and the inhibition of the induction of mouse epidermal ornithine decarboxylase by a tumor promoter.These compounds had bonds corresponding to selected bonds of the E-tetraene chain of retinoic acid (1) held in a planar cisoid conformation by inclusion in an aromatic ring.The meta-substituted analogue 3 of 4-benzoic acid (2) was far less active than 2 in both assays.In contrast, the vinyl homologue of 2 (4) and the 7,8-dihydro and 7,8-methano analogues (5 and 6) had activity comparable to that of 2.Analogues of 4-benzoic acid (7) were also screened.Replacement of the tetrahydronaphthalene ring of 7 by a benzonorbornenyl group (9) significantly reduced activity, as did removal of the vinylic methyl group from 9 (10).Replacement of the propenyl group of 9 by a cyclopropane ring (12) also reduced activity.Replacement of the tetrahydronaphthalene ring of 7 by 4,4-dimethyl-3,4-dihydro-2H-1-benzopyran and -benzothiopyran rings (13 and 14) also decreased activity.Inclusion of the 7,9 double bond system of 1 in an aromatic ring (15 and 16) reduced activity, whereas inclusion of the 5,7 double bond system in an aromatic ring enhanced activity (7 and 19).Inclusion of the 11,13 and 9,11,13 double bond systems in aromatic rings (2 and 18) also reduced activity below that of 1.Retinoic acid, 7, 13, 14, and 19 inhibited papilloma tumor formation in mice.Toxicity testing indicated that 7 was more toxic than 1, 13, 14, and 19, 19 was more toxic than 1, and 13 and 14 were less toxic than 1.
- Dawson, Marcia I.,Hobbs, Peter D.,Derdzinski, Krzysztof,Chan, Rebecca L.-S.,Gruber, John,et al.
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p. 1516 - 1531
(2007/10/02)
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