Asymmetric Synthesis

Valentine, Donald; SCOTT, John W.

doi:10.1055/s-1978-24739

Cited by 224 publications

(33 citation statements)

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“…In order to make clear as to whether this point has any connection with the present study, the rotation was measured under various conditions. It was found that the rotation did not decrease very much even under conditions which destroy hydrogen bonding (Table III, No. 3,4,6). This leads to the conclusion that no particular polymer conformation contributes to the optical rotation observed.…”

Section: Effects Of Measuring Conditions On Optical Rotationmentioning

confidence: 81%

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Asymmetric Reduction of Poly(isopropenyl methyl ketone) via Rhodium(I)-Catalyzed Hydrosilylation

Kawai

Masuda

1981

Polym J

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ABSTRACT:The asymmetric reduction of poly(isopropenyl methyl ketone ) via hydrosilylation gave a new optically active polymer, poly(3-methyl-3-buten-2-ol). The hydrosilylation was carried out with diphenylsilane and a rhodium(!) catalyst containing a chiral phosphine ligand. The effects of the reaction conditions on the optical rotation of the polymer formed were studied in detail. The highest specific rotation reached was + 18.4°, and was attained by the hydrosilylation in 1,4-dioxane at 30°C. On the other hand, both pinacolone (as a monomeric ketone) and a I : I copolymer of isopropenyl methyl ketone with styrene produced the corresponding alcohols having negative small rotations (ca. -3°).KEY WORDS Asymmetric Reduction I Hydrosilylation I Rhodium Complex I Polymer Reaction I Poly(isopropenyl methyl ketone) I Poly(3-methyl-3-buten-2-ol) I Optically Active Polymer I Synthetic optically active polymers are important from the viewpoint of the possibility of applying them to biomimetic polymers, polymer reagents or catalysts for asymmetric reactions, asymmetricselective column materials, and so on. Though extensively investigated, asymmetric-selective polymerization rarely affords highly optically active polymers. 1 On the other hand, as highlighted in the asymmetric synthesis of amino acids, transitionmetal catalyzed asymmetric reactions have made remarkable progress in recent years. 2 -4 Therefore, transition-metal catalyzed asymmetric reactions of polymers seem to provide a feasible method for synthesizing highly optically active polymers.achieved by conducting polymerization and hydrosilylation successively in one pot. 6 We have reported the asymmetric reduction of poly(methyl vinyl ketone) to poly(3-buten-2-ol) via hydrosilylation. 5 Hydrosilylation was performed using either diphenylsilane or a-naphthylphenylsilane, and was catalyzed by a mixture of f.ldichlorotetracyclooctenedirhodium(I) and (-)-2,3-0-isopropylidene-2,3-dihydroxy-1 ,4-bis( diphenylphosphino)butane [(-)-DIOP]. The highest optical rotation of poly (3-buten-2-ol) reached +68°. Further, the direct synthesis of optically active poly(3-buten-2-ol) from methyl vinyl ketone was In the present investigation, the asymmetric reduction of homo-and co-polymers of isopropenyl methyl ketone via hydrosilylation was carried out (see eq 1). The purposes of the present study are to CH

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Section: Effects Of Measuring Conditions On Optical Rotationmentioning

confidence: 81%

“…Following the reaction, tetrahydrofuran (solvent) was replaced by acetone and the hydrosilylation product was hydrolyzed with 1 N hydrochloric acid (4cm 3 ) at room temperature for 1 h, and the organic layer was extracted with ether (30 cm 3 ). The product was isolated by fractional 574 distillation.…”

Section: Methodsmentioning

confidence: 99%

Asymmetric Reduction of Poly(isopropenyl methyl ketone) via Rhodium(I)-Catalyzed Hydrosilylation

Kawai

Masuda

1981

Polym J

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“…For example, comparison of the biological data of compounds 6 and 19, as well as compounds 16 and 29, revealed that B compounds (17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29) are not always superior to A compounds (4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16). Both compounds 29 and 19, which contain a 3,4-dihydro-b-carboline skeleton showed notable difference in activity.…”

Section: Resultsmentioning

confidence: 99%

“…The difficult isolation of manzamine A (3) from sponge and its limited source make this current program more important and significant. A facile synthetic method by the application of Pictet-Spengler reaction [17][18][19][20] and DDQ oxidation 21) allowed the preparation of compounds 4-29. Herein, we wish to report the preparation, characterization and biological evaluation of 1-substituted 1,2,3,4-tetrahydro-and 3,4-dihydro-b-carboline derivatives.…”

Section: )mentioning

confidence: 99%

The Preparation and Evaluation of 1-Substituted 1,2,3,4-Tetrahydro- and 3,4-Dihydro-.BETA.-carboline Derivatives as Potential Antitumor Agents

et al. 2005

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Marine natural products which contain a b-carboline skeleton are widely distributed in marine invertebrates. 1-3)The discovery of natural b-carboline metabolites as potent antitumor and antiviral agents has stimulated great interest in the synthetic and pharmacological studies of b-carboline derivatives. [4][5][6] Particularly interesting targets include such compounds as eudistomins 7,8) and manzamines, 9,10) which were isolated from marine tunicates and sponges, respectively. As a class, the oxathiazepine containing eudistomines exhibited potent inhibitory activity toward DNA virus HSV-1. In addition, the antiviral eudistomines C (1) and E (2) were also found active against HSV-2, the Vaccinia virus and RNA viruses.11) The novel structures of manzamines, however, were reported to possess potent antitumor, 12,13) antibacterial, antifungal, and anti-HIV activities.14) The most active was manzamine A (3), a principal metabolite from several species of sponges, which showed cytotoxicity against murine P-388 cells at 0.07 mg/ml. 15) Our previous report has revealed that manzamine A-D and H exhibited potent cytotoxicities against human KB-16, A-549 and HT-29 tumor cell lines. 16)The common b-carboline or 1,2,3,4-tetrahydro-b-carboline moieties appear to be important for the biological activity. In order to investigate the essential structural features for the antitumor activity of manzamine A (3), the synthesis of 1-substituted 1,2,3,4-tetrahydro-and 3,4-dihydro-b-carboline derivatives were initiated. The difficult isolation of manzamine A (3) from sponge and its limited source make this current program more important and significant. A facile synthetic method by the application of Pictet-Spengler reaction [17][18][19][20] and DDQ oxidation 21) allowed the preparation of compounds 4-29. Herein, we wish to report the preparation, characterization and biological evaluation of 1-substituted 1,2,3,4-tetrahydro-and 3,4-dihydro-b-carboline derivatives. Results and DiscussionAs summarized in Chart 1, compounds 4-16 were synthesized from tryptamine (I) and substituted benzaldehydes via Pictet-Spengler cyclization. Subsequent oxidation of 1,2,3,4-tetrahydro-b-carbolines (4-16, A compounds) by DDQ furnished 3,4-dihydro-b-carboline derivatives (17-29, B compounds). The spectral data for 4-29 are illustrated in Experimental. Table 1 shows the biological results for compounds 4-29 and manzamine A (3) as tested against murine P-388 (leukemia) and human tumor cell lines, including KB-16 (nasopharyngeal carcinoma), A-549 (lung adenocarcinoma) and HT-29 (colon adenocarcinoma) in vitro. All of the compounds exhibited promising activity except for 19, which had no activity toward the four tumor cell lines. Among them, compound 29 exhibited the most potent activity against all tested tumor cells. For P-388 inhibitory activity, compounds 8 and 29 were more potent than or comparable to 3. Compounds 4, 12, 14, 15, 25 and 28 showed potent to moderate activity. As for KB-16 cell cytotoxicity, compound 29 was equal in potency to manzamine A ...

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“…The develop-ment of this higher order criterion for a successful synthesis has esthetic as well as very practical foundations [e.g., the dependence of pharmacological (7) or pheromonal activity (2) on absolute configuration]. The develop-ment of this higher order criterion for a successful synthesis has esthetic as well as very practical foundations [e.g., the dependence of pharmacological (7) or pheromonal activity (2) on absolute configuration].…”

Section: A Introductionmentioning

confidence: 99%