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1.
Shivani Bansal Poonam Gupta A. K. Halve 《Phosphorus, sulfur, and silicon and the related elements》2016,191(7):971-974
We report an efficient and green protocol for the synthesis of 2-oxazolines by the reaction of aromatic nitriles with β-aminoalcohols using sulfur under solvent-free conditions. The reaction occurs via the Willgerodt–Kindler mechanism followed by transamidation and dehydrosulfuration. This methodology offers several advantages such as good yields, mild and practical reaction conditions, simple work-up procedure, and broad substrate scope, which makes the process simple, convenient, and environmental-friendly. 相似文献
2.
[reaction: see text] N-Carbamoylmethyl-N'-tosyl guanidine 2 reacts easily with primary alkylamines to afford substituted carboxamides 3. The reaction proceeds via a five-membered-ring intermediate 5, which could be isolated, and features a rare example of an intermolecular transamidation reaction under mild conditions. 相似文献
3.
The present study reports the preparation and characterisation of Ce(III) immobilised on an aminated epichlorohydrin-activated agarose matrix (CAEA) as a “green” catalyst. The catalyst was synthesised by the reaction of the epichlorohydrin-activated agarose matrix with ammonia solution, which was then treated with Ce(NO3)3 · 6H2O. The catalyst (CAEA) was characterised by FT-IR, far IR, CHN, XRD, TGA, and ICP techniques. CAEA is shown to be an effective and reusable heterogeneous catalyst for the transamidation of carboxamides with amines under solvent-free conditions. The catalyst was successfully applied to the synthesis of a wide range of aromatic and aliphatic amides. High efficiency, mild reaction conditions, easy work-up, simple separation and also reusability are important advantages of this catalyst. 相似文献
4.
The development of an innovative method to access enantiopure 2,4-disubstituted 6-hydroxy-1,6-dihydro-2H-pyridin-3-ones starting from D-glucal via the aza-Achmatowicz transformation has been described. These highly functionalized pyridin-3-ones have been utilized for the synthesis of contiguously substituted pyridines through a rapid and efficient Et(3)N/Ac(2)O promoted cyclo-elimination, aromatization cascade, allowing the facile assembly of important pyridine-based building blocks like 2-substituted 3-acetoxy-4-iodopyridines and enantiopure 2-substituted 3-acetoxy-4-pyridinemethanols possessing benzylic stereogenic centers, whose synthesis otherwise would be tedious. The utilization of commercially available sugars as starting materials, mild reaction conditions, catalytic transfer hydrogen (CTH) of α-furfuryl azide derivatives, transfer of chiral aryl/alkyl methanols from enulosides to pyridin-3-ones and pyridines, high yields, and short reaction times are key features of this method. The utility of the method has been further exemplified by demonstrating the usage of the 2-substituted 3-acetoxy-4-iodopyridine for the construction of biologically significant molecules like 2,7-disubstituted furo[2,3-c]pyridines and 7,7'-disubstituted 2,2'-bifuro[2,3-c]pyridines. 相似文献
5.
I. A. Novakov B. S. Orlinson R. V. Brunilin M. B. Nawrozkij E. A. Gordeeva E. N. Savel‘ev E. N. Gerasimov 《Chemistry of Heterocyclic Compounds》2009,45(11):1365-1369
We have investigated the potential use of a solid-phase synthesis of novel 6-(arylmethyl)-5-methyl-isocytosine derivatives
based on the immobilization of the corresponding 2-thiothymine on a Merrifield resin, oxidation of the immobilized form to
the sulfone, and aminolysis of the latter under mild conditions. 相似文献
6.
D. Chaturvedi A. K. Chaturvedi N. Mishra V. Mishra 《Journal of the Iranian Chemical Society》2009,6(3):510-513
A quick and efficient, one-pot synthesis of carbazates was accomplished in high yields by the reaction of various primary, secondary, and tertiary alkyl halides with a variety of substituted hydrazines using Amberlite IRA 400 basic resin/CO2 system. The reaction conditions were mild with simpler work-up procedures than the previously reported methods. 相似文献
7.
Boutard N Dufour-Gallant J Deaudelin P Lubell WD 《The Journal of organic chemistry》2011,76(11):4533-4545
Aryldiazepin-2-ones are known as "privileged structures", because they bind to multiple receptor types with high affinity. Toward the development of a novel class of aryldiazepin-2-one scaffolds, the synthesis of pyrrolo[3,2-e][1,4]diazepin-2-ones on a support was explored starting from N-(PhF)-4-hydroxyproline and featuring an acid-catalyzed Pictet-Spengler reaction to form the diazepine ring. Three supports [Wang resin, tetraarylphosphonium (TAP) soluble support, and Merrifield resin] were examined in the synthesis of the heterocycle and exhibited different advantages and disadvantages. Wang resin proved effective for exploratory optimization of the synthesis by identification of intermediates after resin cleavage under mild conditions; however, the acidic conditions of the Pictet-Spengler reaction caused premature loss of resin-bound material. Direct monitoring of reactions by TLC, RP-HPLC-MS, and in certain cases NMR spectroscopy was possible with the TAP support, which facilitated purification of intermediates by precipitation; however, incomplete precipitation of material led to overall yields lower than those from solid-phase approaches on resin. Merrifield resin proved stable to the conditions for the synthesis of the pyrrolo[3,2-e][1,4]diazepin-2-one targets and would be amenable to "split-and-mix" chemistry; however, relatively harsh conditions were necessary for final product cleavage. Perspective for the application of different solid-phase approaches in heterocycle library synthesis was thus obtained by demonstration of the respective utility of the three supports for preparation of pyrrolo[3,2-e][1,4]diazepin-2-one. 相似文献
8.
Devdutt Chaturvedi Nisha Mishra Amit K. Chaturvdi Virendra Mishra 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3):550-558
A quick and efficient, one-pot synthesis of dithiocarbazates was accomplished in high yields by the reaction of various alcoholic tosylates of primary, secondary, and tertiary alcohols, with substituted hydrazines using an Amberlite IRA 400 (basic resin)/CS 2 system. The reaction conditions are mild with simpler work-up procedures than previously reported methods. 相似文献
9.
Various thiols are prepared quantitatively from the corresponding thioacetates via Pd catalyzed methanolysis with borohydride exchange resin under a mild and neutral conditions. One-pot synthesis of thiols from alkyl halides through the formation of alkyl thioacetates using thioacetate exchange resin followed by methanolysis is also described. 相似文献
10.
In this article, we described the use of an easily available polymer‐based hafnium chloride and montmorillonite KSF catalyst (HfCl4/KSF‐polyDMAP) in transamidation under relatively mild conditions. This metal catalyst can be easily recovered and reused in this reaction to give the corresponding amides in good yields. 相似文献
11.
The first synthesis of 3-alkyl-5-hydroxycyclohex-2-enones is reported. An intramolecular cyclization by means of an aldolic addition/sulfinate elimination tandem reactions, performed under mild basic conditions was the key step. 相似文献
12.
Kissounko DA Hoerter JM Guzei IA Cui Q Gellman SH Stahl SS 《Journal of the American Chemical Society》2007,129(6):1776-1783
Titanium(IV)-mediated reactions between primary amines and secondary carboxamides exhibit different outcomes, amidine formation versus transamidation, depending on the identity of the TiIV complex used and the reaction conditions employed. The present study probes the origin of this divergent behavior. We find that stoichiometric TiIV, either Cp*TiIV complexes or Ti(NMe2)4, promotes formation of amidine and oxotitanium products. Under catalytic conditions, however, the outcome depends on the identity of the TiIV complex. Competitive amidine formation and transamidation are observed with Cp*TiIV complexes, generally favoring amidine formation. In contrast, the use of catalytic Ti(NMe2)4 (< or =20 mol %) results in highly selective transamidation. The ability of TiIV to avoid irreversible formation of oxotitanium products under the latter conditions has important implications for the use of TiIV in catalytic reactions. 相似文献
13.
Bartosz M. Matysiak Guillermo Monreal Santiago Sijbren Otto 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(40):e202201043
Dynamic combinatorial chemistry is a method widely used for generating responsive libraries of compounds, with applications ranging from chemical biology to materials science. It relies on dynamic covalent bonds that are able to form in a reversible manner in mild conditions, and therefore requires the discovery of new types of these bonds in order to progress. Amides, due to their high stability, have been scarcely used in this field and typically require an external catalyst or harsh conditions for exchange. Compounds able to undergo uncatalysed transamidation at room temperature are still rare exceptions. In this work, we describe reversible amide formation and transamidation in a class of compounds known as maleamic acids. Due to the presence of a carboxylic acid in β-position, these compounds are in equilibrium with their anhydride and amine precursors in organic solvents at room temperature. First, we show that this equilibrium is responsive to external stimuli: by alternating the additions of a Brønsted acid and a base, we can switch between amide and anhydride several times without side-reactions. Next, we prove that this equilibrium provides a pathway for reversible transamidation without any added catalyst, leading to thermodynamic distributions of amides at room temperature. Lastly, we use different preparation conditions and concentrations of Brønsted acid to access different library distributions, easily controlling the transition between kinetic and thermodynamic regimes. Our results show that maleamic acids can undergo transamidation in mild conditions in a reversible and tunable way, establishing them as a new addition to the toolbox of dynamic combinatorial chemistry. 相似文献
14.
Selective transformation of thioamides to their corresponding carbonyl compounds are performed in high to excellent yields
under mild conditions using pyridinium hydrobromide perbromide (PHBP) as a mild and efficient reagent.
Correspondence: Moslem M. Lakouraj, Department of Organic Chemistry, Faculty of Chemistry, Mazandaran University, Babolsar
47416, Iran. 相似文献
15.
Perrotta E Altamura M Barani T Bindi S Giannotti D Harmat NJ Nannicini R Maggi CA 《Journal of combinatorial chemistry》2001,3(5):453-460
A method to prepare 1,3-disubstituted 2,6-diketopiperazines (2,6-DKP) as useful heterocyclic library scaffolds in the search of new leads for drug discovery is described. The method can be used in solution-phase and solid-phase conditions. In the key step of the synthesis, the imido portion of the new molecule is formed in solution through intramolecular cyclization, under basic conditions, of a secondary amide nitrogen on a benzyl ester. A Wang resin carboxylic ester is used as the acylating agent under solid-phase conditions, allowing the cyclization to take place with simultaneous cleavage of the product from the resin ("cyclocleavage"). The synthetic method worked well with several couples of amino acids, independently from their configuration, and was used for the parallel synthesis of a series of fully characterized compounds. The use of iterative conditions in the solid phase (repeated addition of fresh solvent and potassium carbonate to the resin after filtering out the product-containing solution) allowed us to keep diastereoisomer content below the detection limit by HPLC and (1)H NMR (200 MHz). 相似文献
16.
Liqiang Wu Xiaojuan Yang 《Phosphorus, sulfur, and silicon and the related elements》2013,188(6):748-753
Abstract The direct α-thiocyanation of ketones with ammonium thiocyanate has been achieved using pyridinium hydrobromide perbromide under mild and neutral conditions to produce α-ketothiocyanates in excellent yields and with high selectivity. 相似文献
17.
A novel Merrifield resin supported phenanthroline-Cu(I) complex has been developed and used as a highly efficient and recyclable catalyst in the reaction of 2-halobenzenamines with isothiocyanates for the synthesis of 2-aminobenzothiazoles. The reactions were applicable to a variety of 2-halobenzenamines and isothiocyanates, and generated the corresponding 2-aminobenzothiazoles in good yields under mild reaction conditions. Moreover, the catalyst was quantitatively recovered from the reaction mixture by a simple filtration and reused for ten cycles with almost consistent activity. 相似文献
18.
Calter MA Phillips RM Flaschenriem C 《Journal of the American Chemical Society》2005,127(42):14566-14567
Pyrimidine derivatives of the cinchona alkaloids function as excellent asymmetric catalysts for the "Interrupted" Feist-Bénary Reaction. This reaction produces highly substituted hydroxydihydrofurans from simple starting materials under mild conditions. The asymmetric reaction gives high enantioselectivities with unsubstituted bromoketones, and high enantio- and diastereoselectivities with substituted substrates. Mechanistic experiments suggest that the hydrobromide salt of the alkaloid derivative is the active catalyst for the reaction. 相似文献
19.
《Tetrahedron letters》2003,44(16):3255-3257
The synthetic diphosphate Na2CaP2O7 is a new basic catalyst for the synthesis of unsaturated arylsulfones. The condensation was carried out under mild conditions at room temperature in methanol or ethanol. The optimum of the catalyst's activity is reached when water is added, leading to good yields. 相似文献
20.
Preparation of Furo[3,2‐c]coumarins from 3‐Cinnamoyl‐4‐hydroxy‐2H‐chromen‐2‐ones and Acyl Chlorides: A Bu3P‐Mediated C‐Acylation/Cyclization Sequence 下载免费PDF全文
Chia‐Jui Lee Cheng‐Che Tsai Shao‐Hao Hong Geng‐Hua Chang Mei‐Chun Yang Dr. Lennart Möhlmann Prof. Dr. Wenwei Lin 《Angewandte Chemie (International ed. in English)》2015,54(29):8502-8505
A Bu3P‐mediated cyclization reaction of 3‐cinnamoyl‐4‐hydroxy‐2H‐chromen‐2‐ones though electrophilic addition of acyl chlorides towards the synthesis of highly functionalized furo[3,2‐c]coumarins bearing a phosphorus ylide moiety is described. These unprecedented cyclization reaction proceeds under mild reaction conditions within short reaction times (1 min to 1 h), and can be further applied in the synthesis of alkenyl‐substituted furo[3,2‐c]coumarins by the treatment with carbonyl electrophiles under basic conditions. 相似文献