A TfOH-promoted, metal-free protocol has been unveiled for the synthesis of spiro-furan quinazolinones employing alkynol urea derivatives utilizing alkynyl Prins cyclization reaction. This methodology produces highly functionalized spiro-heterocycles in excellent yields with exclusive -selectivity under ambient conditions. Furthermore, late-stage modifications incorporate bromide and acetyl functionalities into the synthesized spiro-heterocycles.
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http://dx.doi.org/10.1039/d3cc04464e | DOI Listing |
European J Org Chem
November 2024
Department of Chemistry, University of Rochester, Rochester, NY 14627.
This manuscript describes a study of diverse reaction outcomes that stem from the ionization of -alkynyl-Prins adducts. Experimental results have demonstrated unexpected behavior in the nitrogen-containing systems compared to the analogous oxygen derivatives derived from -Prins/-Nazarov sequences. In-depth experimental studies and computational analysis revealed an intricate mechanism involving competing -Nazarov and -Nazarov pathways.
View Article and Find Full Text PDFJ Org Chem
October 2024
Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati-781039, Assam, India.
A metal-free, Lewis acid approach for the regioselective synthesis of dihydropyranoquinoline scaffolds has been unveiled. The methodology employs a cascade alkynyl Prins-aza-Michael reaction sequence to deliver the products in good to excellent yields. The strategy features mild reaction conditions, broad substrate scope, and high functional group tolerance.
View Article and Find Full Text PDFOrg Biomol Chem
January 2024
Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati-781039, Assam, India.
An efficient methodology for the synthesis of -(pyrrolidine-3-ylidenemethyl)acetamides mediated by triflic acid in good yields with separable / isomers within a short reaction time has been demonstrated. The reaction involves the initial formation of the pyrrolidin-3-ylidenemethylium carbocation the Prins cyclization reaction followed by the Ritter reaction to produce -(pyrrolidine-3-ylidenemethyl)acetamides. This methodology is also used for the synthesis of their piperidine derivatives.
View Article and Find Full Text PDFJ Org Chem
December 2023
Department of Chemistry, University of Rochester, 120 Trustee Road, Rochester, New York 14611, United States.
This article is a comprehensive report describing our studies in the field of aza-alkynyl Prins chemistry, comparing and contrasting the different reaction partners and reactivities observed during method development. The synthetic strategies combine an alkynyl aza-Prins coupling with an annulation, enabling the preparation of different nitrogen-containing heterocycles. Different iminium ions are explored as viable electrophiles for an alkynyl Prins cyclization, terminated by capture with a halogen nucleophile to form a vinyl halide.
View Article and Find Full Text PDFChem Commun (Camb)
November 2023
Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati-781039, Assam, India.
A TfOH-promoted, metal-free protocol has been unveiled for the synthesis of spiro-furan quinazolinones employing alkynol urea derivatives utilizing alkynyl Prins cyclization reaction. This methodology produces highly functionalized spiro-heterocycles in excellent yields with exclusive -selectivity under ambient conditions. Furthermore, late-stage modifications incorporate bromide and acetyl functionalities into the synthesized spiro-heterocycles.
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