A series of vinylogous imines have been prepared from anilines and cinnamaldehydes. These substrates react in superacidic media to provide quinolines and related compounds. A mechanism for the conversion is proposed which involves the cyclization of dicationic superelectrophilic intermediates. Aromatization of the quinoline ring is thought to occur by superacid-promoted elimination of benzene.
Download full-text PDF |
Source |
---|---|
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7720793 | PMC |
http://dx.doi.org/10.1016/j.tetlet.2020.151630 | DOI Listing |
J Org Chem
January 2023
Department of Chemistry and Biochemistry, Northern Illinois University, DeKalb, Illinois 60115, United States.
A variety of 9,9'-spirobifluorenes and related azaspirocycles and diazaspirocycles have been prepared in high yields by intramolecular Friedel-Crafts reaction using the Brønsted superacid, triflic acid (CFSOH). Compared to weaker Brønsted acids, the superacid consistently provides better yields along with reduced reaction times and it eliminates the need for heating. The superacid is particularly effective when dicationic electrophilic intermediates are generated in the conversions, for example with the diazaspirocycle syntheses.
View Article and Find Full Text PDFTetrahedron Lett
March 2020
Department of Chemistry and Biochemistry, Northern Illinois University, DeKalb, IL 60115.
A series of vinylogous imines have been prepared from anilines and cinnamaldehydes. These substrates react in superacidic media to provide quinolines and related compounds. A mechanism for the conversion is proposed which involves the cyclization of dicationic superelectrophilic intermediates.
View Article and Find Full Text PDFChem Commun (Camb)
June 2020
Institut de Chimie des Milieux et Matériaux de Poitiers (IC2MP), Université de Poitiers, CNRS, Superacid Group in Organic Synthesis Team, F-86073 Poitiers, France.
The superacid-promoted electrophilic Csp3-H bond activation of aliphatic amines generates superelectrophilic species that can be subsequently fluorinated. Demonstrated by low-temperature in situ NMR experiments, the ammonium-carbenium dications, crucial for this reaction, can also react with C-H bonds opening future synthesis perspectives for this mode of activation.
View Article and Find Full Text PDFChemistry
August 2020
Université de Poitiers, UMR-CNRS 7285, IC2MP, Superacid Group - Organic Synthesis Team, 4 rue Michel Brunet, TSA 51106, 86073, Poitiers Cedex 9, France.
Site-selective functionalization of arenes that is complementary to classical aromatic substitution reactions remains a long-standing quest in organic synthesis. Exploiting the generation of halenium ion through oxidative process and the protonation of the nitrogen containing function in HF/SbF , the chlorination and iodination of classically inert Csp -H bonds of aromatic amines occurs. Furthermore, the superacid-promoted (poly)protonation of the molecules acts as a protection, favoring the late-stage selective halogenation of natural alkaloids and active pharmaceutical ingredients.
View Article and Find Full Text PDFChem Commun (Camb)
July 2017
Department of chemistry, The University of Tennessee, Knoxville, Tennessee 37996-1600, USA.
A superacid-promoted "knitting" strategy has been developed for the generation of a novel family of hypercrosslinked nanoporous polycarbazoles for efficient CO capture. Using trifluoromethanesulfonic acid, a Brønsted superacid, we demonstrate the facile and rapid synthesis of highly porous polycarbazoles with BET surface areas as high as 1688 m g, and capable of adsorbing 3.5 mmol g of CO at 298 K and 1 bar.
View Article and Find Full Text PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!