Brønsted Acid-Catalyzed, Highly Enantioselective Addition of Enamides to In Situ<i>-</i>Generated<i>ortho</i>-Quinone Methides: A Domino Approach to Complex Acetamidotetrahydroxanthenes
作者:Satyajit Saha、Christoph Schneider
DOI:10.1002/chem.201406044
日期:2015.2.2
The highly enantioselective conjugate addition of enamides and enecarbamates to in situ‐generated ortho‐quinone methides, upon subsequent N,O‐acetalization, gives rise to acetamido‐substituted tetrahydroxanthenes with generally excellent enantio‐ and diastereoselectivities. A chiral BINOL‐based phosphoric acid catalyst controls the enantioselectivity of the carbon–carbon bond‐forming event. The products
Cooperative Catalysis for the Highly Diastereo‐ and Enantioselective [4+3]‐Cycloannulation of
<i>ortho</i>
‐Quinone Methides and Carbonyl Ylides
作者:Arun Suneja、Henning Jakob Loui、Christoph Schneider
DOI:10.1002/anie.201913603
日期:2020.3.27
We describe herein a highly diastereo- and enantioselective [4+3]-cycloannulation of ortho-quinone methides and carbonyl ylides to furnish functionalized oxa-bridged dibenzooxacines with excellent yields and stereoselectivity in a single synthetic step. The combination of rhodium and chiral phosphoric acid catalysis working in concert to generate both transient intermediates in situ provides direct
Phosphoric Acid Catalyzed [4 + 1]-Cycloannulation Reaction of <i>ortho</i>-Quinone Methides and Diazoketones: Catalytic, Enantioselective Access toward <i>cis</i>-2,3-Dihydrobenzofurans
作者:Arun Suneja、Christoph Schneider
DOI:10.1021/acs.orglett.8b03311
日期:2018.12.7
A highly straightforward route to enantiomerically highly enriched cis-2,3-dihydrobenzofurans has been achieved via addition of α-diazocarbonyl compounds to in situ generated o-QMs catalyzed by a chiral Brønsted acid. This catalytic strategy provides a direct access to 2,3-dihydrobenzofurans in high yields and with up to 91:9 dr and 99:1 er at ambient temperature. Moreover, a unique phenonium-type
Phosphoric Acid Catalyzed Aldehyde Addition to in Situ Generated <i>o</i>-Quinone Methides: An Enantio- and Diastereoselective Entry toward <i>cis</i>-3,4-Diaryl Dihydrocoumarins
作者:Matthias Spanka、Christoph Schneider
DOI:10.1021/acs.orglett.8b01865
日期:2018.8.17
phosphoric acid catalyzed synthesis of cis-3,4-diarylchromanols through reaction of o-hydroxybenzhydryl alcohols and aryl acetaldehydes is reported. The products can be further manipulated to 3,4-dihydrocoumarins, 4H-chromenes, and chromanes with good overall yields and very good diastereo- and enantiocontrol. This reaction is based upon the concept of enol catalysis and comprises the in situ generation
Cooperative Photoinduced/Brønsted Acid Catalyzed Cycloaddition of Transient Thioaldehydes and <i>ortho</i>-Quinone Methides toward a Synthesis of Benzo[<i>e</i>][1,3]oxathiines
作者:Florian Sachse、Christoph Schneider
DOI:10.1021/acs.orglett.1c00588
日期:2021.4.2
in situ generation and ensuing cycloaddition of thioaldehydes and ortho-quinone methides transiently formed under irradiation with UV-A light and Brønsted acid catalysis, respectively, has been developed giving direct access to benzo[e][1,3]oxathiines in good to excellent yields and diastereoselectivity. Both electron-rich and electron-poor thioaldehydes easily react with a broad range of ortho-quinone
已经开发了一种合作的一锅法,用于原位生成并随后分别在UV-A光和Brønsted酸催化下短暂形成的硫代醛和邻醌甲基化物环加成反应,从而可以直接获得苯并[ e ] [ 1,3]氧杂蒽酮具有良好的收率和非对映选择性。富电子和贫电子的硫醛都可以在环境温度下以很短的反应时间轻松地与各种邻苯二甲基甲烷反应,以提供各种S,O-杂环。