- Enantioselective synthesis of the tricyclic furan moeity of azadirachtin, a potent insect antifeedant
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A synthesis of the enantiomerically pure right-hand part (2) of an insect antifeedant, azadirachtin, is described. Reduction with baker's yeast was demonstrated to be efficient for kinetic resolution of racemic diketone (4) to give 3 of ~75% e.e., from which was derived 2 in 11 steps.
- Watanabe, Hidenori,Watanabe, Takeru,Mori, Kenji
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- Metabolic Swiching in Cytochrome P-450cam: Deuterium Isotope Effects on Regiospecificity and the Monooxygenase/Oxidase Ratio
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Cytochrome p-450cam, isolated and purified to homogenity from the soil bacteria Pseudomonas putida, has been shown to catalyze the hydroxylationof the substrate analogue norcamphor to form three distinct products and yields: 5-exo-hydroxynorcamphor (45percent), 6-exo-hydroxynorcamphor (47percent), and 3-exo-hydroxynorcamphor (8percent).Specific deuteriation of the norcamphor skeleton at the 5-,6-,and 3-positons drastically alters this product distribution, indicatinga substantial deuterium isotope effect.When the sum total of all oxygenated products formed in the presence of norcamphor is compared to the number of reducing equivalents consumed in the reaction (NADH), a striking unaccountability of electrons is observed.Thes are shown to reside in excess water produced by the four-electron reduction of atmospheric dioxygen by P-450cam.Metabolismof specifically deuteriated norcamphor demonstrates a deuterium isotope effect on the branching ratio of substrate hydroxylation to excess water production and suggests that this oxidase activity of P-450cam results from thetwo-electron reduction of a single oxygen-iron intermediate, 3+.
- Atkins, William M.,Sligar, Stephen G.
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- Evaluation of the chiral DIANANE backbone as ligand for organolithium reagents
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Novel endo,endo-2,5-diaminonorbonane-derived tertiary C2- symmetrical diamines were synthesized via the one-pot reductive amination of enantiomerically pure norbornane-2,5-dione. These ligands were applied to various catalytic reactions such as asymmetric deprotonation, asymmetric bromine-lithium exchange, and enantioselective addition of aryl- and allkylithium reagents to aromatic aldimines. Copyright
- Praz, Jezabel,Guenee, Laure,Aziz, Sarwar,Berkessel, Albrecht,Alexakis, Alexandre
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p. 1780 - 1790
(2012/07/28)
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- Preparation of C3-symmetric homochiral syn-trisnorbornabenzenes through regioselective cyclotrimerization of enantiopure iodonorbornenes
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C3-symmetric homochiral (-)-syn-trisoxonorbornabenzene 1 possessing a rigid cup-shaped structure was synthesized through a novel regioselective cyclotrimerization of enantiopure iodonorbornenes catalyzed by palladium nanoclusters. The yield of
- Reza, A. F. G. Masud,Higashibayashi, Shuhei,Sakurai, Hidehiro
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scheme or table
p. 1329 - 1337
(2010/04/23)
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- Bicyclic diols and related derivatives as catalysts for the asymmetric diethylzinc addition to benzaldehyde
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Chiral bicyclic diols based on bicyclo[2.2.2]octane and bicyclo[2.2.1]heptane have been synthesized and their catalytic capacity in the asymmetric diethylzinc addition to benzaldehyde compared with those described for previously synthesized 2,6-bicyclo[2.
- Olsson, Cecilia,Friberg, Annika,Frejd, Torbjoern
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p. 1475 - 1482
(2008/12/21)
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- Some new C2-symmetric bicyclo[2.2.1]heptadiene ligands: synthesis and catalytic activity in rhodium(I)-catalyzed asymmetric 1,4- and 1,2-additions
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C2-Symmetric bicyclo[2.2.1]hepta-2,5-dienes with various substituents (R=Bn, i-Bu, c-Hex, allyl) are prepared starting from the corresponding enantiomerically pure bis-triflate (R=OTf). These chiral ligands are tested and compared in rhodium(I)
- No?l, Timothy,Vandyck, Koen,Van der Eycken, Johan
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p. 12961 - 12967
(2008/03/17)
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- Enantioselective Synthesis of DIANANE, a Novel C2-Symmetric Chiral Diamine for Asymmetric Catalysis
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DIANANE (endo,endo-2,5-diaminonorbornane) is a novel chiral C 2-symmetric diamine, based on the rigid bicyclo[2.2.1]heptane scaffold. Schiff-base ligands derived from DIANANE have already found use in asymmetric catalysis, e.g., in the highly e
- Berkessel, Albrecht,Schroeder, Michael,Sklorz, Christoph A.,Tabanella, Stefania,Vogl, Nadine,Lex, Johann,Neudoerfl, Joerg M.
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p. 3050 - 3056
(2007/10/03)
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