- A new chiral sulfonamide ligand based on tartaric acid: synthesis and application in the enantioselective addition of diethylzinc to aldehydes and ketones
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A new sulfonamide ligand based on l-tartaric acid was synthesized and was employed as a chiral ligand in the enantioselective addition of diethylzinc to aldehydes, giving rise to the best enantiomeric excess up to 83% with 5 mol % of catalyst loading. Moreover, the addition of diethylzinc to ketones can also be achieved with good to excellent enantioselectivities by employing 7 mol % of the catalyst under mild conditions.
- Hui, Ailing,Zhang, Jintang,Fan, Jinmin,Wang, Zhiyong
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- Enantioselective α-Hydroxylation by Modified Salen-Zirconium(IV)-Catalyzed Oxidation of β-Keto Esters
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The highly enantioselective α-hydroxylation of β-keto esters using cumene hydroperoxide (CHP) as the oxidant was realized by a chiral (1S,2S)-cyclohexanediamine backbone salen-zirconium(IV) complex as the catalyst. A variety of corresponding chiral α-hydroxy β-keto esters were obtained in excellent yields (up to 99%) and enantioselectivities (up to 98% ee). The zirconium-catalyzed enantioselective α-hydroxylation of β-keto esters was scalable, and the zirconium catalyst was recyclable. The reaction can be performed in gram scale, and corresponding chiral products were acquired in 95% yield and 99% ee.
- Yang, Fan,Zhao, Jingnan,Tang, Xiaofei,Zhou, Guangli,Song, Wangze,Meng, Qingwei
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- Two new phenolic amides from the seeds of Pharbitis nil
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Two new phenolic amides, pharnilatins A (1) and B (2), were isolated from the seeds of Pharbitis nil. These new compounds possess a p-coumaroyl unit with a structurally unique side chain, (2S,3S)-2,3-dihydroxyputrescine. The chemical structures and absolute stereochemistries of the new compounds were determined on the basis of spectroscopic analyses including 1D- and 2D-NMR experiments and chemical reactions. Compounds 1 and 2 exhibited cytotoxicity against A549, SK-OV-3, SK-MEL-2, and HCT-15 human tumor cells. However, none of the compounds inhibited nitric oxide (NO) production in lipopolysaccharide (LPS)-activated microglia cells.
- Kim, Ki Hyun,Choi, Sang Un,Son, Mi Won,Lee, Kang Ro
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- Asymmetric hydrogen-transfer hydrogenation on rhodium(I) complexes with new optically active salen ligands derived from (4S,5S)-4,5-Bis(aminomethyl)-2,2- dimethyl-1,3-dioxolane
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New optically active C2-symmetric salen-type ligands were synthesized on the basis of (4S,5S)-4,5-bis(aminomethyl)-2,2-dimethyl-1,3-dioxolane. These ligands were used to obtain cationic (trifluoromethanesulfonate) and neutral (chloride) rhodium(I) complexes with [(4S,5S)-2,2-dimethyl-5-{[(E)-pyridin-2- ylmethylidene]aminomethyl}-1,3-dioxolan-4-yl]-N-[(E)-pyridin-2-ylmethylidene] methanamine and [2,2-dimethyl-5-{[(E)-quinolin-2-ylmethylidene]aminomethyl}-1,3- dioxolan-4-yl]-N-[(E)-quinolin-2-ylmethylidene] methanamine. The latter complex ensured preparation of (S)-2-phenylethanol with an optical yield of 34.8% by transfer hydrogenation of acetophenone. Pleiades Publishing, Ltd., 2012.
- Nindakova,Shainyan,Badyrova,Lebed'
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- The Detosylation of Chiral 1,2-Bis(tosylamides)
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The deprotection of chiral 1,2-bis(tosylamides) to their corresponding 1,2-diamines is mostly unsuccessful under standard conditions. In a new methodology, the use of Mg/MeOH with sufficient steric additions allows the facile synthesis of 1,2-diamines in 78-98% yields. These results are rationalized using density functional theory and the examination of inner and outer-sphere reduction mechanisms.
- Gaston, Jayden J.,Tague, Andrew J.,Smyth, Jamie E.,Butler, Nicholas M.,Willis, Anthony C.,van Eikema Hommes, Nico,Yu, Haibo,Clark, Timothy,Keller, Paul A.
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p. 9163 - 9180
(2021/07/19)
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- Ring-opening and -expansion of 2,2′-biaziridine: Access to diverse enantiopure linear and bicyclic vicinal diamines
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The chiral pool-derived 1,1′-ditosyl-2,2′-biaziridine has been established as a valuable building block for the divergent synthesis of enantiopure vicinal diamines. Efficient procedures for the regioselective ring opening of the biaziridine with oxygen, sulfur, nitrogen, and carbon nucleophiles are described. The strategic use of nucleophiles bearing pendant functionality allows further elaboration of the acyclic products to a variety of 2,2′-bicyclic-embedded diamines. Desymmetrization of the biaziridine has also been accomplished via the selective monoaddition of organocuprates.
- Bailey, Stephen J.,Wales, Steven M.,Willis, Anthony C.,Keller, Paul A.
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p. 4344 - 4347
(2014/10/16)
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- Cyclic sulfamide HIV-1 protease inhibitors, with sidechains spanning from P2/P2′ to P1/P1′
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Previous studies of HIV protease inhibitors have shown that it is possible to elongate the P1/P1′ sidechains to reach the S3/S3′ binding sites. By analogy, we expected that it would be possible to design inhibitors reaching between the S1/S1′ and S2/S2′ b
- Ax, Anna,Schaal, Wesley,Vrang, Lotta,Samuelsson, Bertil,Hallberg, Anders,Karlén, Anders
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p. 755 - 764
(2007/10/03)
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- CATALYSTS
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Catalysts suitable for asymmetric hydrogenation reactions is described comprising the reaction product of a group (8) transition metal compound a chiral phosphine and a chiral diamine of formula (1) in which R1, R 2 R 3 or R 4 are independently hydrogen, a saturated or unsaturated alkyl, or cycloalkyl group, an aryl group, a urethane or sulphonyl group and R 5 , R 6 , R 7 or R8 are independently hydrogen, a saturated or unsaturated alkyl or cycloalkyl group, or an aryl group, at least one of R1, R 2 , R3 or R 4 is hydrogen and A is a linking group comprising one or two substituted or unsubstituted carbon atoms.
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Page/Page column 19
(2008/06/13)
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- Catalytic asymmetric phase-transfer reactions using tartrate-derived asymmetric two-center organocatalysts
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A new highly versatile asymmetric two-center catalyst, tartrate-derived diammonium salt (TaDiAS), was designed and a catalyst library containing more than 70 new two-center catalysts was constructed. A variety of (S,S)- and (R,R)-TaDiAS were easily synthesized from diethyl L- and D-tartrate, respectively, using common and inexpensive reagents under operationally simple reaction conditions. TaDiAS was used in phase-transfer alkylations and Michael additions to afford various optically active α-amino acid equivalents in up to 93% yield. Moreover, dramatic counter anion effects were observed in phase-transfer catalysis (PTC) for the first time, making it possible to further improve reactivity and selectivity. These findings validate the usefulness of three-dimensional fine-tuning of the catalyst (acetal, Ar, and counter anion) for optimization. Recovery and reuse of the catalyst was also possible using simple procedures. The present asymmetric PTC was successfully applied to enantioselective syntheses of serine protease inhibitor aeruginosin 298-A and its analogues.
- Ohshima, Takashi,Shibuguchi, Tomoyuki,Fukuta, Yuhei,Shibasaki, Masakatsu
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p. 7743 - 7754
(2007/10/03)
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- Diamines having a C2 symmetry. Synthesis and application as ligands in the hydrogenation of prochiral substrates over rhodium complexes
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Chiral diamines having a C2 symmetry, (4S,5S)-2,2-dimethyl-4,5-bis(aminomethyl)-1,3-dioxolane and (5S,5′ S)-2,2,2′,2′-tetramethyl-3,3′-diphenyl-5,5′ -bioxazolidine, were synthesized on the basis of (+)-(2R,3R)-tartaric acid. Their structure was proved by X-ray analysis. The products were used as ligands in rhodium catalyst for enantioselective hydrogenation of α -acetamidocinnamic and itaconic acids.
- Shainyan,Ustinov,Bel'skii,Nindakova
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p. 104 - 110
(2007/10/03)
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- Development of new asymmetric two-center catalysts in phase-transfer reactions
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A new asymmetric two-center phase-transfer catalyst was designed and a catalyst library containing more than 40 new two-center catalysts was constructed. The catalysts were applied in phase-transfer alkylations and Michael additions to afford the correspo
- Shibuguchi, Tomoyuki,Fukuta, Yuhei,Akachi, Yoko,Sekine, Akihiro,Ohshima, Takashi,Shibasaki, Masakatsu
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p. 9539 - 9543
(2007/10/03)
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- New supramolecular host systems, 11. The stereoisomeric diaminobutanediol and dioxadiazadecalin systems: Synthesis, structure, stereoelectronics, and conformation - Theory vs. experiment
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We present new approaches to the (C2) chiral and meso 1,4-diamino-2,3- butanediol (1) and 2,3-diamino-1,4-butanediol (2) and derivatives. Reactions of these compounds with aldehydes to form the novel 1,5-dioxa-3,7- diazadecalin (DODAD) and 1,5-diaza-3,7-dioxadecalin (DADOD) classes of compounds (7, 9, 11-15) are also reported. These reactions are diastereospecific, i e, erythro (meso) or threo starting compounds lead to trans or cis products, respectively. The structural, conformational, and stereoelectronic aspects of these systems were probed experimentally and computationally and provided excellent insight into their properties and behaviour. Good agreement was observed between X-ray, NMR, and calculated results of the N,N'-dibenzyl derivatives of trans-DODAD (14) and trans-DADOD (15).
- Star, Alexander,Goldberg, Israel,Lemcoff, N. Gabriel,Fuchs, Benzion
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p. 2033 - 2043
(2007/10/03)
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- Platinum(II) complex and processes for preparing the same
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Disclosed herein are novel platinum(II) complexes having a potent anti-tumor activity which are represented by the formula (1), STR1 wherein R1 and R2, which may be the same or different, are a hydrogen atom or a C1-4 alkyl group, respectively, or jointly form a cycloalkane group together with the carbon atom attached thereto; two Xs jointly form a group represented by formula (a) or (b) wherein, R3 is a hydrogen atom or a methyl group; R4 and R5, which may be the same or different, are a hydrogen atom or a C1-4 alkyl group, respectively, or jointly form a cyclobutane together with the carbon thereto; and the absolute configurations at the respective chiral centers in the 4,5-bis(aminomethyl)-1,3-dioxolane moiety are (4R,5R) or (4S,5S); processes for the preparing the same; and their use for treating animal or human cancer. Further, disclosed herein are novel intermediates useful for the preparation of the platinum(II) complexes and processes for preparing said intermediates.
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- Analogues of Cisplatin Derived from Diaminodeoxytetritols. Synthesis and Activity against the ADJ/PC6 Plasmacytoma in Mice
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Four new analogues of the anticancer drug cisplatin have been prepared that contain a diaminodideoxytetritol derivative as the amine ligand moiety, and their acitivities have been measured against the ADJ/PC6 plasmacytoma in mice.Two of these compounds, the enantiomers of cis-dichloro(1,4-diamino-1,4-dideoxy-2,3-O-isopropylidenethreitol)platinum(II), show a higher TI value than cisplatin when administered by intraperitoneal injection and, importantly, show significant antitumor acitivity when administered orally.
- Haines, Alan H.,Morley, Christopher,Murrer, Barry A.
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p. 742 - 745
(2007/10/02)
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- Platinum coordination compounds
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Coordination compounds of platinum(II) with 4,5-bis(aminomethyl)-1,3-dioxolane, intended for use in the treatment of cancer. The compounds may exist as monomers or as linear or cyclic polymers.
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