- Manganese catalysts with C1-symmetric N4 ligand for enantioselective epoxidation of olefins
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Bioinspired manganese complexes based on N4 ligands, with a more rigid, chiral diamine derived from proline and two benzimidazoles, were synthesized and applied to epoxidize olefins with hydrogen peroxide as a clean oxidant. Notably, 60-99 % isolated yields and excellent ee values (up to 95 %) were obtained by using low catalyst loadings (0.01-0.2 mol %; see scheme; F green, S yellow). Copyright
- Wang, Bin,Miao, Chengxia,Wang, Shoufeng,Xia, Chungu,Sun, Wei
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p. 6750 - 6753
(2012/07/03)
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- Synthesis, characterisation and in vitro cytotoxicity studies of a series of chiral platinum(II) complexes based on the 2-aminomethylpyrrolidine ligand: X-ray crystal structure of [PtCl2(R-dimepyrr)] (R-dimepyrr = N-dimethyl-2(R)-aminomethylpyrrolidine)
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A series of platinum(II) complexes were synthesised based on the enantiomerically pure amino acid proline. Novel synthetic pathways were developed, adapted from standard peptide chemistry, to produce the 2-aminomethylpyrrolidine (pyrr) ligand and its derivatives with differing arrangements of methyl substituents at the exocyclic amine sites. The crystal structure of [PtCl2(R-dimepyrr)] (R-dimepyrr = N,N-dimethyl-2(R)-aminomethylpyrrolidine) is reported and the five-membered ligand ring has been shown to be in an envelope conformation. Cytotoxicity studies were carried out on the ovarian cancer A2780 tumour cell line and its cisplatin-resistant variant, A2780cisR. Remarkably good activity was seen for several of the drugs when compared to cisplatin despite the addition of substantial steric bulk to the amine groups, and there was a lack of cross-resistance with cisplatin seen for some compounds.
- Diakos, Connie I.,Zhang, Mei,Beale, Philip J.,Fenton, Ronald R.,Hambley, Trevor W.
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experimental part
p. 2807 - 2814
(2009/10/10)
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- Compounds binding to the S2-S3 pockets of thrombin
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A set of compounds designed to bind to the S2-S3 pockets of thrombin was prepared. These compounds included examples with no interactions in the S1 pocket. Proline, a common P2 in many thrombin inhibitors, was combined with known P3 residues and P1 substituents of varying size and lipophilicity. Binding constants were determined using surface plasmon resonance (SPR) biosensor technology and were found to be in good agreement with results from an enzyme assay. A dramatic increase in affinity (100-1000 times) was seen for compounds incorporating an amino group capable of forming a hydrogen bond with gly216 in the protein backbone. The ligand efficiency was increased by including substituents that form stronger hydrophobic interactions with the P1 pocket. The binding mode was confirmed by X-ray analysis, which revealed the anticipated binding motif that included hydrogen bonds as well as a tightly bound water molecule. A QSAR model indicated that hydrogen bonding and lipophilicity were important for the prediction of binding constants. The results described here may have implications for how directed compound libraries for shallow protein pockets, like S2 and S3 in serine proteases, can be designed.
- Nilsson, Mikael,H?m?l?inen, Markku,Ivarsson, Maria,Gottfries, Johan,Xue, Yafeng,Hansson, Sebastian,Isaksson, Roland,Fex, Tomas
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experimental part
p. 2708 - 2715
(2010/01/16)
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- Effects of glycosylation of (2S,4R)-4-hydroxyproline on the conformation, kinetics, and thermodynamics of prolyl amide isomerization
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Glycosylation (galactosylation) of (2S,4R)-4-hydroxyproline (Hyp) in the peptide mimic N-acetyl-Hyp-N′-methylamide does not mediate the isomer equilibrium nor the rate of isomerization between the cis- and trans-prolyl amides in water. However, glycosylat
- Owens, Neil W.,Braun, Craig,O'Neil, Joe D.,Marat, Kirk,Schweizer, Frank
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p. 11670 - 11671
(2008/03/13)
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- Factors Affecting Conformation in Proline-Containing Peptides
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(Equation presented) NMR was used to study the thermodynamics of the cis → trans isomerization for prolyl amide bonds in the compounds shown. The magnitude of Kt/c for C-terminal esters is greater than for the corresponding amides, signifying s
- Taylor, Carol M.,Hardre, Renaud,Edwards, Patrick J. B.,Park, Jae H.
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p. 4413 - 4416
(2007/10/03)
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- Synthesis of phosphoramides for the lewis base-catalyzed allylation and aldol addition reactions
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Both chiral and achiral phosphoramides of diverse structure were prepared from diamines by the coupling to phosphorus(V) or phosphorus(III) reagents. Several enantiopure 1,2-diphenyl-1,2-ethanediamine analogues have been prepared by the reductive coupling of the corresponding N-silylimine with NbCl4(THF)2 and subsequent resolution by the formation of diastereomeric menthyl carbamates. (S,S)-N,N'-Di-(1-naphthyl)-1,2-diphenyl- 1,2-ethanediamine 15 was prepared by the arylation of (S,S)-1,2-diphenyl- 1,2-ethanediamine with naphthyl iodide.
- Denmark, Scott E.,Su, Xiping,Nishigaichi, Yutaka,Coe, Diane M.,Wong, Ken-Tsung,Winter, Stephen B. D.,Choi, Jun Young
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p. 1958 - 1967
(2007/10/03)
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- Synthesis of peptides containing a sulfinamide or a sulfonamide transition-state isostere
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A versatile synthesis of peptides incorporating the sulfinamide or sulfonamide transition-state analogue is described. Apart from the easily accessible Gly-Xxx isosteres used as haptens to elicit catalytic antibodies, other amino acids than Gly can be prepared by α-alkylation of the sulfonamide containing peptides. This is illustrated with the synthesis of a potential HIV-protease inhibitor 27.
- Moree, Wilna J.,Van Gent, Liesbeth C.,Van Der Marel, Gijs A.,Liskamp, Rob M. J.
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p. 1133 - 1150
(2007/10/02)
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- PREPARATION, SPECTRAL AND PHYSICOCHEMICAL CHARACTERISTICS OF METHYLAMIDE Nα-PHENYLTHIOCARBAMOYL DERIVATIVES OF NATURALLY OCCURING AMINO ACIDS
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The methylamide Nα-phenylthiocarbamoyl derivatives of encoded amino acids II were prepared either by the addition of phenylisothiocyanate to amino acid methylamides or by the treatment of amino acid phenylthiohydantoins (5-alkyl-3-phenyl-2-thioxo-4-imidazolinones) I with methylamine.The derivatives were prepared of 19 amino acids and their melting points, 1H NMR, 13C NMR, mass, ultraviolet and infrared spectra were measured.
- Pavlik, Manfred,Kluh, Ivan,Pavlikova, Frantiska,Vasickova, Sona,Kostka, Vladimir
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p. 1940 - 1954
(2007/10/02)
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- 211. Scope and Limitations of the Reductive Coupling of Aromatic Aldimine Derivatives with Formation of 1,2-Diarylethylenediamine Units, Using Low-Valent Titanium Reagents
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Besides the adducts from lithium amides to aromatic aldehydes, iminium salts, aminals, and N-silylimines of aromatic aldehydes are coupled by the black suspension obtained from TiCl4 and Mg turnings in tetrahydrofuran (THF).The 1,2-diarylethylenediamines with tertiary and primary amino groups thus obtained are formed with no or only moderate diastereoselectivity (products 4a-d (Scheme 2) and 5a-e (Scheme 3), respectively); the amine component may contain a strained ring or additional heteroatoms as in azetidin, bis(2-metoxyethyl)amine piperazine, morpholine, and thiomorpholine (products 6a-e; Table 1).By an in-situ procedure, ethylenediamines and propane-1,3-diamines with two secondary amino groups are cyclized with aromatic aldehydes to give exclusively trans-diaryl-substituted piperazine and perhydro-1,4-diazepine derivatives (products 7a-f; Table 2).Enantiomerically pure monocyclic trans,cis-5-alkyl-2,3-diaryl-piperazines and diazabicyclononanes and -decanes are obtained by employing suitable diamines prepared from the amino acids (S)-alanine, (S)-phenylalanine, (S)-proline, and from (S,S)- or (R,R)-cyclohexane-1,2-diamine, respectively (products 11a-i, 7e; Table 4).The configurations of all products are derived from the high-field NMR spectra, some of which are discussed in detail (Figs. 1 and 2, Tables 3 and 5); all new compounds are fully characterized by their physical data.Depending upon the structure of the components employed, the yields of purified products range from as low as 7percent to essentially quantitative.
- Betschart, Claudia,Schmidt, Beat,Seebach, Dieter
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p. 1999 - 2021
(2007/10/02)
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- CARBENE COMPLEXES XIX. OPTICALLY ACTIVE ELECTRON-RICH OLEFIN-DERIVED CARBENE-TRANSITION-METAL COMPLEXES. CRYSTAL STRUCTURES OF , , AND
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Several optically active electron-rich olefins L2* have been prepared from readily available chiral starting materials, such as (S)-α-amino-acids (e.g., (S)-leucine) or terpene derivatives (e.g., (+)- or (-)-3-pinanecarboxylic acid).The derived carbene-transition-metal complexes (17 monocarbene RhI, 1 bis(carbene)RhI, and a d8 Co complex) have been prepared with retention of optical integrity; some of their chemical and spectroscopic properties are described.X-Ray structures of four transition-metal complexes bearing optically active carbene ligands (L*) derived from (S)-proline, (R)-(-)-trans-N,N'-dimethyl-1,2-diaminocyclohexane, (S)-leucine, or (S)-alanine, respectively are also reported: cis*Me)>, cis-*Me)>, trans-iL*Me)(PPh3)2>, and *Me)(NO)(PPh3)>.
- Coleman, Anthony W.,Hitchcock, Peter B.,Lappert, Michael F.,Maskell, Robin K.,Mueller, Joachim H.
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p. 173 - 196
(2007/10/02)
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