A facile chiral phosphoric-acid catalyzed asymmetric inverse-electron-demand aza-Diels-Alder reaction of 1,3-diazadienes with 3-vinylindoles was established. By using this mild and practical protocol, a broad range of benzothiazolopyrimidines with three contiguous stereogenic centers were prepared in good yields and excellent diastereo- and enantio-selectivities (43 examples, up to 83% yield, >99% ee and all >20 : 1 dr). A plausible concerted reaction pathway enabled by the dual hydrogen-bonding effect was proposed to account for the observed excellent enantioselectivity and specific - diastereoselectivity.
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http://dx.doi.org/10.1039/d2cc02458f | DOI Listing |
Beilstein J Org Chem
December 2024
Departamento de Química Orgánica y Química Inorgánica, Instituto de Investigación Química "Andrés M. del Río" (IQAR), Universidad de Alcalá (IRYCIS), 28805 Madrid, Spain.
Asymmetric cycloaddition is a straightforward strategy which enables the synthesis of structurally distinct cyclic derivatives which are difficult to access by other methodologies, using an efficient and atom-economical path from simple precursors. In recent years several asymmetric catalytic cyclization strategies have been accomplished for the construction of -heterocycles using various catalytic systems such as chiral metal catalysts, chiral Lewis acids or chiral organocatalysts. This review presents an overview of the recent advances in enantioselective cyclization reactions of 1-azadienes catalyzed by non-covalent organocatalysts.
View Article and Find Full Text PDFJ Am Chem Soc
November 2024
Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470, Mülheim an der Ruhr, Germany.
Chiral 1,3-amino alcohols are ubiquitous structural motifs in natural products and active pharmaceutical ingredients. We present a highly enantioselective, inverse-electron-demand hetero-Diels-Alder reaction of olefins with in situ generated -Boc-formaldimine catalyzed by strong and confined Bro̷nsted acids. This transformation provides direct access to valuable 1,3-amino alcohols from styrenes and 1,1-disubtituted alkenes.
View Article and Find Full Text PDFChem Sci
March 2024
Key Laboratory of Green Chemistry & Technology, Ministry of Education, College of Chemistry, Sichuan University Chengdu 610064 P. R. China
The asymmetric catalytic inverse-electron-demand hetero-Diels-Alder reaction of dioxopyrrolidines with a variety of simple olefins has been accomplished, significantly expanding the applicability of this cyclization to both cyclic hetero-dienes and dienophiles. A new type of strong Lewis acid catalyst of ferric salt enables the LUMO activation of dioxopyrrolidines formation of cationic species, this method yields a range of bicyclic dihydropyran derivatives with exceptional outcomes, including high yields (up to 99%), diastereoselectivity (up to 99 : 1) and enantioselectivity (up to 99% ee) under mild conditions. This facile protocol was available for the late-stage modification of several bioactive molecules and transformation into macrocycle molecules as well.
View Article and Find Full Text PDFChem Sci
November 2023
Department of Chemistry and Research Center for Molecular Recognition and Synthesis, Fudan University 220 Handan Rd. Shanghai 200433 China
We report herein the collective asymmetric total synthesis of seven pentacyclic 19--clerodane diterpenoids, namely (+)-teucvin (+)-cracroson A, (+)-cracroson E, (+)-montanin A, (+)-teucvisin C, (+)-teucrin A, and (+)-2-hydroxyteuscorolide. An ytterbium-catalyzed asymmetric inverse-electron-demand Diels-Alder reaction of 4-methyl-2-pyrone with a chiral C5-substituted cyclohexa-1,3-dienol silyl ether is the key feature of the synthesis, which provides the common -decalin intermediate with five continuous stereocenters in excellent yield and stereoselectivity. From this diversifiable intermediate, the total synthesis of (+)-teucvin and (+)-2-hydroxyteuscorolide was realized in thirteen and eighteen steps, respectively.
View Article and Find Full Text PDFJ Am Chem Soc
November 2023
Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States.
Novel asymmetric aminocatalytic cycloadditions are described between formyl cycloheptatrienes and 6,6-dimethylfulvene that lead to [4 + 2], [6 + 2], and [4 + 6] cycloadducts. The unprecedented reaction course is dependent on the position of the formyl functionality in the cycloheptatriene core, and each formyl cycloheptatriene isomer displays a distinct reactivity pattern. The formyl cycloheptatriene isomers are activated by a chiral primary diamine catalyst, and the activation mode is dependent on the position of the formyl functionality relative to the cycloheptatriene core.
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