A series of pyrano[3,2-]quinolone derivatives has been synthesized in the presence of taurine (2-aminoethanesulfonic acid) as a green bio-organic catalyst and water as the solvent. The target compounds were synthesized through the three-component reaction between aldehydes, malononitrile/ethylcyanoacetate, and 4-hydroxy-1-methyl-2(1)-quinolone. The advantages of this protocol are excellent yields of products, short reaction times, cost efficiency, atom economy, and a simple work-up procedure with no need for extra purification techniques. Moreover, the catalyst can be easily recovered and reused for up to three cycles without losing any significant activity.
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http://dx.doi.org/10.1021/acs.joc.2c01403 | DOI Listing |
RSC Adv
January 2025
Department of Organic Chemistry, University of Debrecen Egyetem Square 1 Debrecen 4032 Hungary
Domino Knoevenagel-cyclization reactions of styrene substrates, containing an -(-formyl)aryl subunit, were carried out with -substituted 2-cyanoacetamides to prepare tetrahydro-4-pyrano[3,4-]quinolone and hexahydrobenzo[]phenanthridine derivatives by competing IMHDA and IMSDA cyclization, respectively. The diastereoselective IMHDA step with α,β-unsaturated amide, thioamide, ester and ketone subunits as a heterodiene produced condensed chiral tetrahydropyran or thiopyran derivatives, which in the case of Meldrum's acid were reacted further with amine nucleophiles in a multistep domino sequence. In order to simplify the benzene-condensed tricyclic core of the targets and get access to hexahydro-1-pyrano[3,4-]pyridine derivatives, a truncated substrate was reacted with cyclic and acyclic active methylene reagents in diastereoselective Knoevenagel-IMHDA reactions to prepare novel condensed heterocyclic scaffolds.
View Article and Find Full Text PDFCarbohydr Res
May 2024
Bioorganic Laboratory, Department of Chemistry, University of Delhi, Delhi, 110007, India. Electronic address:
Herein, we report the development of a diastereoselective and efficient route to construct sugar-derived pyrano[3,2-c]quinolones utilizing 1-C-formyl glycal and 4-hydroxy quinolone annulation. This methodology will open a route to synthesize nature inspired pyrano[3,2-c]quinolones. This is the first report for the stereoselective synthesis of sugar-derived pyrano[3,2-c]quinolones, where 100% stereoselectivity was observed.
View Article and Find Full Text PDFJ Org Chem
November 2022
Department of Chemistry, University of Rajasthan, Jaipur 302004, Rajasthan, India.
A series of pyrano[3,2-]quinolone derivatives has been synthesized in the presence of taurine (2-aminoethanesulfonic acid) as a green bio-organic catalyst and water as the solvent. The target compounds were synthesized through the three-component reaction between aldehydes, malononitrile/ethylcyanoacetate, and 4-hydroxy-1-methyl-2(1)-quinolone. The advantages of this protocol are excellent yields of products, short reaction times, cost efficiency, atom economy, and a simple work-up procedure with no need for extra purification techniques.
View Article and Find Full Text PDFThis study deals with the synthesis of the regioselective and facile domino one-pot four-component reaction of 2-chloroquinoline-3-carbaldehydes, 1, 3-cyclodione compounds (as cyclic active methylene), ethyl acetoacetate (as β-keto ester), and hydrazine hydrate in the presence of DABCO as a homogeneous organocatalyst yielding a novel series of 4H-pyrano[2, 3-b]quinolones. This multicomponent reaction has some advantages; the significant one is C-O bond formation under metal-free conditions. Other benefits include simple procedure, mild and green condition, high yield, easy purification, and excellent regioselectivity.
View Article and Find Full Text PDFRSC Adv
July 2022
Department of Chemistry, Institute of Synthesis and Application of Medical Materials, Chunhui Scientific Research Interest Group, Wannan Medical College Wuhu 241002 China.
Two acid-catalyzed tandem reactions between 4-hydroxy-1-methylquinolin-2(1)-one and propargylic alcohols are described. Depending mainly on the propargylic alcohol used, these tandem reactions proceed either a Friedel-Crafts-type allenylation followed by 6--dig cyclization sequence to form pyrano[3,2-]quinolones or a Friedel-Crafts-type alkylation and 5--dig ring closure sequence to afford furo[3,2-]quinolones in moderate-to-high yields. The pyrano[3,2-]quinolones products could be further transformed to tetracyclic 4,9-dihydro-5-cyclopenta[]phenanthridin-5-one derivatives.
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