- Diastereomeric (η4-diene)Fe(CO)3 complexes containing chiral amide groups: A convenient method for the resolution of amino acids
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Diastereomeric (η4-N-substituted-hexa-2,4-dienamide)-Fe(CO) 3 complexes bearing chiral amide groups were used for the resolution of (η4-dienecarboxylic acid)Fe(CO)3 complexes. Using the latter, enantiomerically pure proteinogenic or nonproteinogenic a-amino acids were prepared. Georg Thieme Verlag Stuttgart.
- Schumacher, Marc,Coste, Gerald,Miesch, Laurence
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- A synthesis-enabled relative stereochemical assignment of the C1-C28 region of hemicalide
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Through synthesising both candidate diastereomers of a model C1-C28 fragment of the potent cytotoxic marine polyketide hemicalide, an assignment of the relative configuration between the C1-C15 and C16-C26 regions has been achieved. By detailed NMR comparisons with the natural product, the relative stereochemistry between these two 1,6-related stereoclusters is elucidated as 13,18-syn rather than the previously proposed 13,18-anti relationship. A flexible and modular strategy using an advanced C1-C28 ketone fragment 22 is outlined to elucidate the remaining stereochemical features and achieve a total synthesis.
- Han, Bing Yuan,Lam, Nelson Y. S.,MacGregor, Callum I.,Goodman, Jonathan M.,Paterson, Ian
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- Conformational Analysis of Open-Chain 1,2:3,4-Diepoxides: Comparison of Crystal Structures, NMR Data, and Molecular-Orbital Calculations
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Several pairs of diastereomeric open-chain 1,2:3,4-diepoxides with different substitution patterns were prepared (see 3-9).As far as possible, crystal structures were determined to corroborate the relative configurations and to give insight into the solid-state conformations of these compounds.The comparison with our earlier molecular-orbital calculations and with 1H-NMR measurements shows that the solid-state conformations of eight out of the nine open-chain 1,2:3,4-diepoxides, whose crystal structures had been determined, correspond to substituted diepoxides of the erythro-series (e-6, e-7, e-9) seem to prefer the same conformation as in the crystal.The solution conformations of all other diepoxides differ from the arrangement in the solid state.
- Bur, Daniel,Nikles, Martin,Sequin, Urs,Neuburger, Martin,Zehnder, Margareta
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- Bioinspired intramolecular diels-alder reaction: A rapid access to the highly-strained cyclopropane-fused polycyclic skeleton
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A bioinsipred gold-catalyzed tandem Diels-Alder/Diels-Alder reaction of an enynal and a 1,3-diene, forming the highly-strained benzotricyclo[3.2.1.0 2,7]octane skeleton, was reported. In contrast, a Diels-Alder/Friedel-Crafts tandem reaction occurred instead when silver salts were used as the catalyst. Although both reactions experienced the similar Diels-Alder reaction of a pyrylium intermediate with a 1,3-diene, they have different reaction mechanisms. The former proceeded with a stepwise Diels-Alder reaction, while the latter one with a concerted one. Mother nature knows best! A gold-catalyzed reaction of enynals and 1,3-dienes, giving rapid access to the highly strained benzotricyclo[3.2.1.02,7]octane skeleton, is reported (see scheme; QMD=quinodimethane). Owing to the mild reaction conditions, excellent substrate scope, and high functional-group tolerance, this system holds potential for the construction of complex molecules with the tricyclo[3.2.1.02,7]octane skeleton. Copyright
- Zhu, Shifa,Guo, Zhengjiang,Huang, Zhipeng,Jiang, Huanfeng
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supporting information
p. 2425 - 2430
(2014/03/21)
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- Benzo[e]isoindole-1,3-diones as potential inhibitors of glycogen synthase kinase-3 (GSK-3). Synthesis, kinase inhibitory activity, zebrafish phenotype, and modeling of binding mode
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Benzo[e]isoindole-1,3-dione derivatives were synthesized, and the effects on GSK-3β activity and zebrafish embryo growth were evaluated.Aseries of derivatives show obvious inhibitory activity against GSK-3β. The most potent inhibitor, 7,8-dimethoxy-5-methylbenzo[e]isoindole-1,3-dione (8a), shows nanomolar IC50 and obvious phenotype on zebrafish embryo growth associated with the inhibition of GSK-3β at low micromolar concentration. The interaction mode between 8a and GSK-3β was characterized by computational modeling. 2009 American Chemical Society.
- Zou, Haixia,Zhou, Liyan,Li, Yuanzhen,Cui, Yi,Zhong, Hanbing,Pan, Zhengying,Yang, Zhen,Quan, Junmin
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supporting information; experimental part
p. 994 - 1003
(2010/08/06)
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- Regioselective Palladium-catalysed Amination of 4-Chloroacetoxyalk-2-enoic Esters: Synthesis of Pyrrol-2(5H)-ones (4-but-2-enelactams)
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Palladium(0)-catalysed reactions of 4-chloroacetoxyalk-2-enoic esters with amines selectively give 4-aminoalk-2-enoic esters, which are readily converted into pyrrol-2(5H)-ones (4-but-2-enelactams).
- Tanikaga, Rikuhei,Takeuchi, Jun,Takyu, Masayuki,Kaji, Aritsune
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p. 386 - 387
(2007/10/02)
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- THE MECHANISM OF REACTIONS OF ORGANOPALLADIUM SALTS WITH VINYLCYCLOPROPANES
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Cyclopropylmercuric chloride, lithium chloropalladite and methyl acrylate react at 0-25 deg C to give an 81percent yield of methyl sorbate.A ?-allylic palladium intermediate is proposed since vinylcyclopropane, carbomethoxymercuric acetate, and lithium chloropalladate give the same product.The corresponding reactions with styrene and cyclopropylmercuric chloride or vinylcyclopropane and phenylmercuric chloride also give the same, isolable ?-allylic palladium complex.Deuterium labeling experiments support the occurrence of a common intermediate in the two reactions. 1,1-Dicarboethoxy-2-vinylcyclopropane reacts similarly with "phenylpalladium chloride" but the ?-allylic product has the palladium attached at the benzyl carbon rather than the next carbon away.The reaction with "phenylpalladium acetate" in place of the chloride yields only dienes.Studies with the deuterated vinylcyclopropane diester suggest that the mode of elimination from the initial palladium adduct is strongly influenced by the anion present.The reaction of "cyclopropylpalladium chloride" with alkenes appears to be a general method for preparing, selectively, internal ?-allylic palladium complexes.
- Fischetti, William,Heck, Richard F.
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p. 391 - 405
(2007/10/02)
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- An Improved and Convenient Synthesis of Esters Using 1,1'-Carbonyldiimidazole and a Reactive Halide
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The esterification of carboxylic acid proceeded easily in a one-pot reaction with 1,1'-carbonyldiimidazole in the presence of a reactive halide under neutral reaction conditions in high yields. Keywords - esterification: 1,1'-carbonyldiimidazole; formylation; tert-butyl ester; imidazolium salt; one-pot reaction
- Kamijo, Tetsuhide,Harada, Hiromu,Iizuka, Kinji
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p. 5044 - 5047
(2007/10/02)
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