A highly regioselective DBU-catalyzed [3 + 2] annulation of Morita-Baylis-Hillman carbonates with isothiocyanates was developed. This method allows rapid and efficient synthesis of spirocyclic oxindole dihydrothiophene products in moderate to high yields with excellent regioselectivities under simple conditions. A plausible reaction mechanism is also proposed.
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http://dx.doi.org/10.1021/acs.joc.6b01315 | DOI Listing |
J Org Chem
January 2025
School of Chemistry, University of Hyderabad, C. R. Rao Road, Gachibowli, Hyderabad 500 046, India.
A facile two-step enantiospecific synthesis of 5,6,7,8-tetrahydroindolizine scaffolds has been developed via TMSOTf-promoted [3 + 2] cycloaddition between carbohydrate-derived spirocyclic donor-acceptor cyclopropanecarboxlates and alkyl/aryl nitriles followed by an intramolecular Mitsunobu reaction of the resulting chiral 2/5-(4-hydroxybutyl)pyrrole derivatives.
View Article and Find Full Text PDFChemSusChem
January 2025
Lomonosov Moscow State University: Moskovskij gosudarstvennyj universitet imeni M V Lomonosova, Department of Chemistry, Leninskie Gory, 1-3, 119991, Moscow, RUSSIAN FEDERATION.
Spirocyclic alkyl amino carbene (SCAAC) Ru complexes demonstrate outstanding activity and selectivity in ethenolysis of methyl oleate (MO) or fatty acid methyl esters (FAMEs), and 5,6-dimethoxyindane derivative was the most active catalyst to date. For the further catalyst design, we proposed modifying the spirocyclic fragment by fusion of saturated carbo- or heterocycle, linked to the 5,6-positions of indane or 6,7- positions of tetralin. Another suggested way of the modification of SCAAC complex was the insertion of chromane fragment to the carbene ligand.
View Article and Find Full Text PDFJ Org Chem
January 2025
Department of Chemistry, Central University of Punjab, Bathinda 151401, India.
Visible-light-driven metal- and photocatalyst-free cascade 1,4-HAT and dearomative spirocyclization of -benzylacrylamides are described for sustainable synthesis of a variety of pharmaceutically important γ-ketoamides and 2-Azaspiro[4.5]decanes in one pot in good to excellent yields. Readily accessible and nontoxic materials, expensive Ir or Ru photocatalyst-free mild conditions, excellent functional group tolerance, operational simplicity, and scalability enhance the practical value of this protocol.
View Article and Find Full Text PDFSynthesis of complex, multiring, spirocyclic, 1,3-dicarbonyl fused, and highly functionalized 5-phenyl-1-azabicyclo[3.1.0]hexanes (ABCH) has been achieved by an intermolecular reaction of 2-(2'-ketoalkyl)-1,3-indandiones or α,γ-diketo esters with (1-azidovinyl)benzenes under transition metal-free conditions.
View Article and Find Full Text PDFTagging RNAs with fluorogenic aptamers has enabled imaging of transcripts in living cells, thereby revealing novel aspects of RNA metabolism and dynamics. While a diverse set of fluorogenic aptamers has been developed, a new generation of aptamers are beginning to exploit the ring-opening of spirocyclic rhodamine dyes to achieve robust performance in live mammalian cells. These fluorophores have two chemical states: a colorless, cell-permeable spirocyclic state and a fluorescent zwitterionic state.
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