- Boron-Templated Dimerization of Allylic Alcohols to Form Protected 1,3-Diols via Acid Catalysis
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We report an unprecedented boron-templated dimerization of allylic alcohols that generates a 1,3-diol product with two stereogenic centers in high yield and diastereoselectivity. This acid-catalyzed reaction is achieved via in situ formation of a boronic ester intermediate that facilitates selective cyclization and formation of a cyclic boronic ester product. High yields are observed with a variety of allylic alcohols, and mechanistic studies confirm the role of boron as a template for the reaction.
- Nazari, S. Hadi,Forson, Kelton G.,Martinez, Erin E.,Hansen, Nicholas J.,Gassaway, Kyle J.,Lyons, Nathan M.,Kenney, Karissa C.,Valdivia-Berroeta, Gabriel A.,Smith, Stacey J.,Michaelis, David J.
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supporting information
p. 9589 - 9593
(2019/12/02)
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- Visible-Light Promoted Distereodivergent Intramolecular Oxyamidation of Alkenes
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The visible-light-promoted diastereodivergent intramolecular oxyamination of alkenes is described to construct oxazolindinones, pyrrolidinones and imidazolidones via mild generation of primary amidyl radicals from functionalized hydroxylamines. A unique phenomenon of highly diastereoselective ring-opening of aziridines controlled by electron sacrifices was observed. Highly diastereoselective amino alcohols derivatives were obtained efficiently through this protocol in gram scales. The mechanistic studies suggested the isolatable anti-aziridine intermediates were generated quickly from primary amidyl radicals and the diastereoselectivities were controlled by pKavalues of the electron sacrifices.
- Ren, Xiang,Guo, Qihang,Chen, Jianhui,Xie, Hujun,Xu, Qing,Lu, Zhan
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supporting information
p. 18695 - 18699
(2016/12/26)
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- New and facile approach for the synthesis of (E)-α,β-unsaturated esters and ketones
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A general and practical synthesis of (E)-α,β-unsaturated esters and ketones was achieved by the reaction of carbonyl compounds with ethyl-4,4,4-trifluoroacetoacetate and trifluoro-substituted 1,3-diketones in the presence of piperidine in dichloromethane at raoom temperature (≈40°C) with excellent stereoselectivity (see scheme).
- China Raju, Bhimapaka,Suman, Pathi
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supporting information; experimental part
p. 11840 - 11842
(2011/01/12)
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- Mass spectrometric screening of enantioselective Diels-Alder reactions
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(Chemical Equation Presented) A rapid cat. scan: Mass spectrometric monitoring of reaction intermediates of the retro-Diels-Alder reaction has allowed the rapid screening of catalysts for enantioselective Diels-Alder reactions (see scheme). Copper catalysts as well as metal-free organocatalysts were tested. A protocol for the simultaneous screening of catalyst mixtures has also been developed, which offers new possibilities for high-throughput catalyst development.
- Teichert, Antje,Pfaltz, Andreas
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experimental part
p. 3360 - 3362
(2009/02/07)
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- Discovery of potent, orally available vanilloid receptor-1 antagonists. Structure-activity relationship of N-aryl cinnamides
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The vanilloid receptor-1 (TRPV1 or VR1) is a member of the transient receptor potential (TRP) family of ion channels and plays a role in regulating the function of sensory nerves. A growing body of evidence demonstrates the therapeutic potential of TRPV1 modulators, particularly in the management of pain. As a result of our screening efforts, we identified (E)-3-(4-tert- butylphenyl)-N-(2,3-dihydrobenzo[b][1,4]dioxin-6-yl)acrylamide (1), an antagonist that blocks the capsaicin-induced and pH-induced uptake of 45Ca2+ in TRPV1-expressing Chinese hamster ovary cells with IC50 values of 17 ± 5 and 150 ± 80 nM, respectively. In this report, we describe the synthesis and structure-activity relationship of a series of N-aryl cinnamides, the most potent of which (49a and 49b) exhibit good oral bioavailability in rats (Foral = 39% and 17%, respectively).
- Doherty, Elizabeth M.,Fotsch, Christopher,Bo, Yunxin,Chakrabarti, Partha P.,Chen, Ning,Gavva, Narender,Han, Nianhe,Kelly, Michael G.,Kincaid, John,Klionsky, Lana,Liu, Qingyian,Ognyanov, Vassil I.,Tamir, Rami,Wang, Xianghong,Zhu, Jiawang,Norman, Mark H.,Treanor, James J. S.
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- Novel titanium(IV) chloride catalyzed olefination of aldehydes: A simple and convenient synthesis of trans-cinnamic acids
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A variety of aromatic aldehydes were stereoselectively transformed into (E)-cinnamic acids via the reaction with ethyl bromoacetate and triphenylphosphine in the presence of catalytic amount of titanium tetrachloride, followed by hydrolysis and crystallization.
- Basavaiah, Deevi,Jaganmohan Rao, Anumolu
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p. 195 - 201
(2007/10/03)
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- Kinetic resolution of acyclic secondary allylic silyl ethers catalyzed by chiral ketones
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Kinetic resolution of acyclic secondary allylic silyl ethers by chiral dioxiranes generated in situ from chiral ketones (R)-1 and (R)-2 and Oxone was investigated. An efficient and catalytic method has been developed for kinetic resolution of those substrates with a CCl3, tert-butyl, or CF3 group at the α-position. In particular, high selectivities (S up to 100) were observed for kinetic resolutions of racemic α-trichloromethyl allylic silyl ethers 7 and 9-15 catalyzed by ketones (R)-2. Both the recovered substrates and the resulting epoxides were obtained in high enantiomeric excess. On the basis of steric and electrostatic interactions between the chiral dioxiranes and the racemic substrates, a model was proposed to rationalize the enantioselectivities and diastereoselectivities in the chiral ketone-catalyzed kinetic resolution process.
- Yang,Jiao,Yip,Lai,Wong
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p. 4619 - 4624
(2007/10/03)
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