Synthesis Of 4H-pyrans Research Articles

Withdrawal Notice: MgAl2O4 Spinel-type as Highly Efficient Catalyst for One-pot Synthesis of 4H-pyrans

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Lignosulfonate, A Promising Biomass-Based Building Block in the Preparation of Recyclable Nanocomposite and Its Application in Condensation Reactions

Lignosulfonate is an efficient biomass-based building block, formed an efficient Fe3O4@LS nanocomposite with enormous applications. Concerning environmental and economic aspects, our research focused on the application of Fe3O4@LS nanocomposite as the metal-free catalyst in the synthesis of 4H-pyrans and 4-phenyl-pyridines. The structure and morphology of Fe3O4@LS nanocomposite were completely characterized by Fourier transforms infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDX) field emission scanning electron microscopy (FE-SEM), vibration-sample magnetometer (VSM), X-ray diffraction (XRD) thermal gravimetric analysis (TGA) and back titration method. Also, the structure of synthesized 4H-pyrans and 4-phenyl-pyridines were characterized by FTIR, nuclear magnetic resonance (NMR), and their melting points. This procedure has significant advantages included into high yields, short reaction time and easy operation.

Recent Advances in the Synthesis of 2H-Pyrans.

In this review, we discuss the nature of the different physicochemical factors affecting the valence isomerism between 2H-pyrans (2HPs) and 1-oxatrienes, and we describe the most versatile synthetic methods reported in recent literature to access to 2HPs, with the only exception of 2HPs fused to aromatic rings (i.e., 2H-chromenes), which are not included in this review.

Knoevenagel Reactions of Indole-3-carbaldehyde. Synthesis of 3-Substituted Indole Derivatives

The Knoevenagel condensations of 1H-indole-3-carbaldehyde with various CH acids gave a number of substituted 3-(1H-indol-3-yl)acrylonitriles and acrylamides which were alkylated to afford the corresponding N-alkyl derivatives. The latter were used as Michael acceptors in the synthesis of 4H-pyran, pyridine, 5,6,7,8-tetrahydroquinoline, and [1,3]thiazolo[3,2-a]pyridine derivatives containing an indole fragment.

H5BW12O40 as a green and efficient homogeneous but recyclable catalyst in the synthesis of 4H-Pyrans via multicomponent reaction

H5BW12O40 as a green and efficient homogeneous but recyclable catalyst in the synthesis of 4H-Pyrans via multicomponent reaction

Graphitic Carbon Nitride–Magnetite Nanocatalyst for the Synthesis of 4H-Pyrans

Graphitic Carbon Nitride–Magnetite Nanocatalyst for the Synthesis of 4H-Pyrans

New application of decaniobate salt as basic solid in the synthesis of 4H-pyrans by microwave assisted multicomponent reactions

This study focuses on the search of new applications of polyoxometalates known as decaniobate ions [Nb10O28]6−. The decaniobates can be used as basic solid catalysts in multicomponent reactions to obtain good yields to 4H-pyrans (> 95%) under microwave radiation and solvent-free conditions, using several aldehydes with different electron-withdrawing or electron donor substituents. The synthesis of (TMA)6 [Nb10O28]6H2O was performed following a simple protocol (HPNb), which was modified to decrease the number of hexaniobate species that are formed as impurities (HPNb-HF).

Snail shell as a new natural and reusable catalyst for synthesis of 4H-Pyrans derivatives

Article history: Received October 21, 2015 Received in revised form December 20, 2015 Accepted 7 April 2016 Available online 7 April 2016 A simple, efficient and general method for the synthesis of 4H-pyrans is established through a multi component cyclocondensation of aromatic aldehydes, malononitrile and ethyl acetoacetate or acetyl acetone using snail shell as a natural catalyst. In this method the snail shell was used as green and reusable natural catalyst. Excellent yields, short reaction times and availability of the catalyst are the advantages of this method. © 2016 Growing Science Ltd. All rights reserved.

N,2-Dibromo-6-chloro-3,4-dihydro-2H-benzo[e][1,2,4]thiadiazine-7-sulfonamide 1,1-dioxide: an efficient and homogeneous catalyst for one-pot synthesis of 4H-pyran, pyranopyrazole and pyrazolo[1,2-b]phthalazine derivatives under aqueous media

DCDBTSD was successfully applied in the synthesis of 4H-pyran, pyranopyrazole and pyrazolo[1,2-b]phthalazine derivatives by a one-pot multi-component reaction in water.

Green One-Pot Synthesis of 2H-Pyrans Under Solvent-Free Conditions Catalyzed by Ethylenediammonium Diacetate

Ethylenediammonium diacetate readily catalyzes the Knoevenagel-type condensation between 1,3-dicarbonyl substrates and α,β-unsaturated aldehydes at room temperature under solvent-free conditions. This rapid, efficient, and convenient one-pot approach to the synthesis of 2H-pyrans stands as a significant advance over previously reported protocols. This environmentally friendly methodology has been successfully applied to the synthesis of biologically active natural products of interest zanthosimuline, N-methylflindersine, and ferprenin. Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications ® to view the free supplemental file.

Solvent-free synthesis of 2H-pyrans: One-pot reactions of dithiocarbamates, alkyl propiolates, and isocyanides

A novel, convenient, and an efficient approach to the synthesis of 2H-pyrans has been reported based on the multicomponent reaction. Solvent-free condition for the reaction of dithiocarbamates, alkyl propiolates and isocyanides lead to the formation of 2H-pyrans in good yields. In these reactions, synthesis of 2H-pyrans is possible based on the one-pot reaction and without using any catalyst. The mild reaction conditions and high yields of the products exhibit the good synthetic advantage of these methods. J. Heterocyclic Chem., lpar;2011).

Solvent-free one-pot synthesis of pyrane derivatives

A straightforward and an efficient method for the synthesis of 2H-pyrans via the one-pot, reaction of alkyl bromides, carbon disulfide, secondary amines, activated acetylenes and isocyanides under solvent-free conditions without using any catalyst at room temperature is reported. The method offers several advantages including high yields of products and an easy work-up procedure. J. Heterocyclic Chem., (2011).

ChemInform Abstract: The First Asymmetric Synthesis of Polyfunctionalized 4H-Pyrans via Michael Addition of Malononitrile to 2-Acyl Acrylates.

Abstract Starting from (R)-2,3-O-isopropylideneglyceraldehyde, the first asymmetric synthesis of 4H-pyrans ( 4 ) has been developed; a detailed X-ray structural and stereochemical study has established as R the absolute configuration at the new stereocenter in compounds 4 .

Cycloaddition Reactions of (Z)-β-Siloxyacrylonitriles with Enones: Synthesis of 4H-Pyrans and Dihydro-2H-pyrans

Reaction of (Z)-β-siloxyacrylonitriles 1 with enones 2 afforded 4H-pyrans 3 and dihydro-2H-pyrans 4 regio- and stereoselectively. A concerted hetero-Diels-Alder process is proposed.

Synthesis of 4H-pyrans by O-cyclization of 1,5-diketones

Substituted 4H-pyrans were obtained in high preparative yields by the reaction of 1,5-diketones with acetic anhydride and boron trifluoride etherate in diethyl ether. It is assumed that the heterocyclization of 1,5-diketones includes a step involving the formation and transformations of an acyloxy carbonium ion.

Reaction of 2,4,6-Trimethylpyrylium Salt with Organocopper Reagents: Selective Synthesis of 4H-Pyrans

La reaction d'alkylation ou arylation se fait en position-4 du pyranne avec une bonne regioselectivite (4H/2H≥7/3). Transformation one-pot des 4H-pyrannes en cyclohexene-2ones