- Practical acetalization and transacetalization of carbonyl compounds catalyzed by recyclable PVP-I
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A novel PVP-I catalyzed acetalizations/transacetalizations of carbonyl compounds has been developed processing with a mild and easy handling fashion. Different types of Acyclic and cyclic acetals were prepared from carbonyl compounds or their acetals successfully. Further applications of newly developed catalytic combination were testified. This protocol featured with simplicity of operation, mild reaction condition, short reaction time, recyclable of catalyst and broad substrates scope with excellent yields.
- Cao, Fu-Rong,Lu, Guangying,Ren, Jiangmeng,Wang, Di,Zeng, Bu-Bing
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- Chemoenzymatic macrocycle synthesis using resorcylic acid lactone thioesterase domains
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A key missing tool in the chemist's toolbox is an effective biocatalyst for macrocyclization. Macrocycles limit the conformational flexibility of small molecules, often improving their ability to bind selectively and with high affinity to a target, making them a privileged structure in drug discovery. Macrocyclic natural product biosynthesis offers an obvious starting point for biocatalyst discovery via the native macrocycle forming biosynthetic mechanism. Herein we demonstrate that the thioesterase domains (TEs) responsible for macrocyclization of resorcylic acid lactones are promising catalysts for the chemoenzymatic synthesis of 12- to 18-member ring macrolactones and macrolactams. The TE domains responsible for zearalenone and radicicol biosynthesis successfully generate resorcylate-like 12- to 18-member macrolactones and a 14-member macrolactam. In addition these enzymes can also macrolactonize a non-resorcylate containing depsipeptide, suggesting they are versatile biocatalysts. Simple saturated omega-hydroxy acyl chains are not macrocyclized, nor are the alpha-beta unsaturated derivatives, clearly outlining the scope of the substrate tolerance. These data dramatically expand our understanding of substrate tolerance of these enzymes and are consistent with our understanding of the role of TEs in iterative polyketide biosynthesis. In addition this work shows these TEs to be the most substrate tolerant polyketide macrocyclizing enzymes known, accessing resorcylate lactone and lactams as well as cyclicdepsipeptides, which are highly biologically relevant frameworks.
- Heberlig, Graham W.,Brown, Jesse T. C.,Simard, Ryan D.,Wirz, Monica,Zhang, Wei,Wang, Meng,Susser, Leah I.,Horsman, Mark E.,Boddy, Christopher N.
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supporting information
p. 5771 - 5779
(2018/08/22)
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- Practical synthesis of (E)-α,β-unsaturated carboxylic acids using a one-pot hydroformylation/decarboxylative Knoevenagel reaction sequence
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Combining the regioselective room temperature/ambient pressure hydroformylation and a modification of the Doebner-Knoevenagel reaction allowed for the development of an efficient, one-pot procedure for the synthesis of (E)-α,β-unsaturated carboxylic acids. The reaction proceeds under mild conditions, tolerates a variety of functional groups and gives (E)-α,β-unsaturated carboxylic acids in good yields and with excellent regio-and stereocontrol. The practicability of this process has been demonstrated by a short protecting group-free synthesis of the queen honeybee pheromones 9-ODA[( E)-9-oxodec-2-enoic acid] and 9-HDA[( E)-9-hydroxydec-2-enoic acid].
- Kemme, Susanne T.,?mejkal, Tomá?,Breita, Bernhard
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supporting information; experimental part
p. 989 - 994
(2009/05/27)
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- Silanyl-n-alkanal compounds, method for production and use thereof
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The invention relates to ω-silanyl n-alkanal compounds, method for production and use thereof in the funtionalisation of solid supports, solid supports funtionalised by the compounds and the use of solid supports thus funtionalised for the immobilization and/or synthesis of biological molecules of interest.
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Page/Page column 5
(2008/06/13)
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- Chemoselectivity in the ruthenium-catalyzed redox isomerization of allyl alcohols
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Adjustment of oxidation level by internal hydrogen reorganization represents a highly efficient synthetic protocol. Cyclopentadienylbis(triphenylphosphine)ruthenium chloride in the presence of triethylammonium hexafluorophosphate catalyzes the redox isomerization of allyl alcohols to their saturated aldehydes or ketones. High chemoselectivity is observed since simple primary and secondary alcohols and isolated double bonds are not affected by this catalyst. The reaction is sensitive to the degree of substitution on the double bond and requires relatively unhindered olefins. Switching to indenylbis(triphenylphosphine)ruthenium chloride in the presence of triethylammonium hexafluorophosphate significantly expands the scope of the reaction to substrates bearing more substituted olefinic linkages and to cyclic substrates of rings containing eight or more members. The mechanism is probed by deuterium labeling, which shows that the metal catalyzes an intramolecular 1,3-hydrogen shift of the carbinol hydrogen to the terminal olefinic position.
- Trost, Barry M.,Kulawiec, Robert J.
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p. 2027 - 2036
(2007/10/02)
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