Search results for "HETEROCYCLES"
showing 10 items of 117 documents
Catalytic Asymmetric Formal [3+2] Cycloaddition of 2-Isocyanatomalonate Esters and Unsaturated Imines: Synthesis of Highly Substituted Chiral γ-Lacta…
2017
[EN] Unlike their isocyano and isothiocyanato analogues, isocyanato esters remain almost unexplored as formal 1,3-dipoles in asymmetric catalytic reactions. The first asymmetric formal [3+2] cycloaddition involving isocyanato esters and electrophilic alkenes is reported. Diisopropyl 2-isocyanatomalonate reacts with a,b-unsaturated N-(o-anisidyl) imines in the presence of a Mg(OTf)2¿BOX complex to give highly substituted chiral pyrrolidinones featuring a conjugate exocyclic double bond with excellent yields and enantiomeric excesses up to 99%. Several transformations of the resulting heterocycles, including the synthesis of a pyroglutamic acid derivative, have been carried out.
Eight-membered heterocycles with two heteroatoms in a 1,2-relationship of interest in medicinal chemistry
2021
Abstract This chapter treats 1,2-diheterocines, eight membered heterocyclic systems with two heteroatoms, N, O and S, in an 1,2 relationship, exhibiting biological properties and exhaustively covers the literature from 2007 to the end of November 2019. In this period of time 1,2-diazocine, 1,2-oxazocine, 1,2-dioxocin and 1,5-dithiocin ring systems had derivatives exhibiting pharmacological activities. No articles on biological properties have been reported for 1,2-thiazocines and 1,2-oxathiocins. Besides uncondensed derivatives, 1,2-diheterocines fused with five-, six-, and seven-membered carbocycles or heterocycles have been reviewed, as well as bridged 1,2-diheterocines.
An ANRORC approach to the synthesis of perfluoroalkylated 1,2,4-triazole-carboxamides
2009
A series of perfluoroalkyl-1,2,4-triazole-carboxamides has been obtained through an ANRORClike rearrangement (Addition of Nucleophile, Ring-Opening and Ring-Closure) of 5- perfluoroalkyl-1,2,4-oxadiazole-3-carboxamides with methylhydrazine or hydrazine. The initial addition of the bidentate nucleophile to the electrophilic C(5) of the 1,2,4-oxadiazole ring, followed by ring opening and ring closure, leads to the formation of triazoles in good yield under mild experimental conditions. In some cases, a competitive ANRORC-enlargement reaction to form 1,2,4-triazin-6-ones was also observed. Obtained carboxamidotriazoles have also been explored as precursors for the synthesis of 3(5)-perfluoroal…
Selective and Scalable Electrosynthesis of 2H-2-(Aryl)-benzo[d]-1,2,3-triazoles and Their N-Oxides by Using Leaded Bronze Cathodes.
2020
Abstract Electrosynthesis of 2H‐2‐(aryl)benzo[d]‐1,2,3‐triazoles and their N‐oxides from 2‐nitroazobenzene derivatives is reported. The electrolysis is conducted in a very simple undivided cell under constant current conditions with a leaded bronze cathode and a glassy carbon anode. The product distribution between 2H‐2‐(aryl)benzo[d]‐1,2,3‐triazoles and their N‐oxides can be guided by simply controlling the current density and the amount of the charge applied. The reaction tolerates several sensitive functional groups in reductive electrochemistry. The usefulness and the applicability of the synthetic method is demonstrated by a formal synthesis of an antiviral compound.
Imidazolium and Potassium Hydrogen Carbonate Salts as Ecofriendly Organocatalysts for Oxazolidinone Synthesis
2016
International audience; Although oxazolidinones are valuable intermediate compounds for industrial applications, no synthetic method is suitable for their production on a large scale owing to the use of reagents/catalysts that are hazardous or toxic to human health or ecotoxic for the environment. In this manuscript, we describe new and efficient catalysts, that is, the nontoxic hydrogen carbonate anion in combination with a potassium or diisobutylimidazolium ([iBu(2)IM]) countercation, for the conversion of -amino alcohols into cyclic oxazolidinones in high yields of 69 to 90%. Depending on the catalytic conditions, both catalysts could be easily recovered from the crude reaction products …
The new era of 1,2,4-oxadiazoles
2009
The synthesis, the chemical and photochemical reactivity, and the use of 1,2,4-oxadiazoles in materials and as bioactive compounds have been reviewed. The material in this survey includes some historical background, general features, state-of-the-art applications together with a critical discussion about current limitations and suggestions for future developments.
A Highly Luminescent Nitrogen-Doped Nanographene as an Acid- and Metal-Sensitive Fluorophore for Optical Imaging.
2021
Dibenzo[hi,st]ovalene (DBOV) has excellent photophysical properties, including strong fluorescence and high ambient stability. Moreover, the optical blinking properties of DBOV have enabled optical super-resolution single-molecule localization microscopy with an imaging resolution beyond the diffraction limit. Various organic and inorganic fluorescent probes have been developed for super-resolution imaging, but those sensitive to pH and/or metal ions have remained elusive. Here, we report a diaza-derivative of DBOV (N-DBOV), synthesized in eight steps with a total yield of 15%. Nitrogen (N)-bearing zigzag edges were formed through oxidative cyclization of amino groups in the last step. UV-v…
Straightforward One-Pot Synthesis of New 4-Phenyl-1,2,5,6-tetraazafluoranthen-3(2H)-one Derivatives: X-ray Single Crystal Structure and Hirshfeld Ana…
2022
A straightforward one-pot route for the synthesis of a new 4-phenyl-1,2,5,6-tetraazafluoranthen-3(2H)-one is reported form the direct hydrazinolysis of triketo ester and hydrazine hydrate in ethanol. 4-Phenyl-1,2,5,6-tetraazafluoranthen-3(2H)-one was subjected to aza-Michael addition and N-alkylation on reaction with a set of alkylating agents in the presence of K2CO3. Hydrazinolysis of 4-phenyl-1,2,5,6-tetraazafluoranthen-3(2H)-one ester to hydrazide and conversion of hydrazide to thiosemicarbazide were successful. X-Ray single crystals analysis and 1H, 13C NMR were used for unambiguous structure confirmation. The O…H, N…H, C…N and C…C in 2, and the N…H, …
FDA-Approved Fluorinated Heterocyclic Drugs from 2016 to 2022
2023
The inclusion of fluorine atoms or heterocyclic moiety into drug structures represents a recurrent motif in medicinal chemistry. The combination of these two features is constantly appearing in new molecular entities with various biological activities. This is demonstrated by the increasing number of newly synthesized fluorinated heterocyclic compounds among the Food and Drug Administration FDA-approved drugs. In this review, the biological activity, as well as the synthetic aspects, of 33 recently FDA-approved fluorinated heterocyclic drugs from 2016 to 2022 are highlighted.
Radical addition to iminium ions and cationic heterocycles
2014
Carbon-centered radicals represent highly useful reactive intermediates in organic synthesis. Their nucleophilic character is reflected by fast additions to electron deficient C=X double bonds as present in iminium ions or cationic heterocycles. This review covers diverse reactions of preformed or in situ-generated cationic substrates with various types of C-radicals, including alkyl, alkoxyalkyl, trifluoromethyl, aryl, acyl, carbamoyl, and alkoxycarbonyl species. Despite its high reactivity, the strong interaction of the radical’s SOMO with the LUMO of the cation frequently results in a high regioselectivity. Intra- and intermolecular processes such as the Minisci reaction, the Porta react…