Application of SBA-Pr-SO3H in the synthesis of benzoxazole derivatives (original) (raw)
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Poly (Ethylene Glycol)-Bound Sulphonic Acid as a Novel Catalyst for Synthesis of Benzoxazoles
South African journal of chemistry. Suid-Afrikaanse tydskrif vir chemie
A highly efficient, simple and rapid method for the preparation of various 2-aminobenzoxazoles and other benzoxazole derivatives using a catalytic amount of poly (ethylene glycol)-bound sulphonic acid (PEG-SO 3 H) is described. PEG-SO 3 H is found to be economical and reusable catalyst with low catalytic loading. The percentage yield was found to be satisfactory, experimental set-up and purification of final products is facile and easy. GRAPHICAL ABSTRACT KEYWORDS Poly (ethylene glycol)-bound sulphonic acid (PEG-SO 3 H), 2-aminobenzoxazole, benzoxazole derivatives.
South African Journal of Chemistry Suid Afrikaanse Tydskrif Vir Chemie, 2013
A highly efficient, simple and rapid method for the preparation of various 2-aminobenzoxazoles and other benzoxazole derivatives using a catalytic amount of poly (ethylene glycol)-bound sulphonic acid (PEG-SO 3 H) is described. PEG-SO 3 H is found to be economical and reusable catalyst with low catalytic loading. The percentage yield was found to be satisfactory, experimental set-up and purification of final products is facile and easy.
BiCl3 – an eco-friendly catalyst for an efficient synthesis of benzoxazoles at room temperature
Chemistry of Heterocyclic Compounds, 2015
Several biologically active organic compounds possessing antitumor, antimicrobial, and antiviral properties contain benzoxazole ring system in their structure. 1 2-Substituted benzoxazole derivatives can be synthesized by using two popular methods. The first method involves coupling of 2-aminophenols with carboxylic acid derivatives and is catalyzed by strong acids 2 or requires microwave condition to occur. 3 The second method is the oxidative cyclization of phenolic Schiff bases obtained from the condensation of 2-aminophenols and aldehydes. In this method, various oxidants such as DDQ, 4 Mn(OAc) 3 , 5 PhI(OAc) 2 , 6 ThClO 4 , 7 BaMnO 4 , 8 NiO 2 9 have been used. The literature survey shows that benzoxazoles also have been synthesized using nanosized metal oxides 10a-d and different Lewis acids such as FeCl 3 , CeCl 3 as catalysts. 10e-f These important pharmacophores have also been obtained via the nucleophilic addition and metal-free ortho-C-H functionalization pathways. 10g-h All these synthetic pathways suffer from one or more disadvantages, such as requirement of catalyst in stoichiometric proportion or lengthy and complicated procedure. Therefore, there is a need of more efficient and cost-effective method to synthesize benzoxazole derivatives. In the view of the above considerations we wish to report a simple and efficient method to prepare 2-aryl-and 2-hetarylbenzoxazoles from 2-aminophenol and aromatic aldehydes in the presence of catalytic amount of anhydrous bismuth trichloride in acetonitrile at room temperature (Scheme 1). Bismuth(III) salts are considered as eco
Research on Chemical Intermediates, 2017
Pyruvic acid contains three different reactive positions:-COOH, ketone carbonyl and methyl groups. Correspondingly, pyruvic acid was applied as starting material in the modified Niementowski reaction and Aldol condensation using SBA-Pr-SO 3 H as an efficient nanocatalyst. Aldol condensation of pyruvic acid and oxindole provided a new oxindol-based carboxylic acid which was subsequently used in the Ugi four-component reaction. Moreover, through the modified Niementowski reaction of pyruvic acid, new derivatives of quiazoline were produced in the presence of SBA-Pr-SO 3 H. The obtained products are important due to their potentially biological active skeletons.
PMA/SiO 2 : An efficient synthesis of 2-substituted 1,3-benzazoles by green approach
2014
A mild, efficient and an eco-friendly method is described to synthesis of 1,3-benzazole by Phosphomolybdic acid supported on silica gel (PMA/SiO 2) facilitated reaction of 1,2-phenylenediamine / 2-aminothiophenol with alkyl/aryl aldehydes with excellent yield. A variety of benzazoles derivatives were prepared by using this green methodology in good yields and PMA/SiO 2 was found to be an inexpensive and reusable catalyst.
Synlett
Considering their growing attention in the field of medicinal chemistry and drug-discovery research, the facile and convenient approaches towards the preparation of 2-aryl benzoxazole derivatives have been described. The transformation is accomplished by using Fe(III)-catalyzed C–H activation of benzoxazoles with boronic acids to obtain a wide range of C2-arylated benzoxazoles in high yields. The developed method excludes the formation of self-coupling compounds as side products. On the other hand, the synthesis of the products is also achieved via a metal-free domino protocol by the reaction between 1-nitroso-2-naphthol and acetophenones using catalytic amounts of CBr4 in the presence of Cs2CO3 as base. The devised tandem method avoids the use of pre-activated α-haloketones as substrates. Due to their immense impact in marketed drugs and molecules under clinical trial, the described method can be a powerful tool for their synthesis which restricts the use of precious metals as cat...
Journal of The Iranian Chemical Society, 2016
alkaloid with antimalarial properties extracted from Dichroa febrifuga, was firstly synthesized by McLaughlin and coworkers (Fig. 1) [3]. In the view of their importance and useful properties, several procedures for preparing of 2,3-dihydroquinazolin-4(1H)-ones have been reported in the past few years, such as: (1) the reaction of aldehydes or ketones with anthranilamide using Lewis or Brønsted acids as the catalyst [5, 6]; (2) the reductive cyclization of 2-nitrobenzamide with different aldehydes or ketones by the use of SnCl 2 as the catalyst [7]; (3) the reaction of primary amine (or ammonium salts) and isatoic anhydride, with aldehydes or ketones using Lewis or Brønsted acids as the catalyst [8-10]. Natural or artificial ultraviolet (UV) light is responsible for the destruction and decomposition of organic compounds, the dyes discoloration and the loss of mechanical properties in polymeric compounds and plastics [11]. Many efforts have been made to improve the durability of these materials upon exposure to UV light. The use of organic UV absorbers in the matrices of the mentioned materials is one of the most convenient and effective methods to avoid their photoaging [12]. The organic UV absorbers must, of necessity, be colorless compounds and absorb UV light in the range of 280 and 400 nm [13]. SBA-15, as a mesoporous silica, was synthesized by Zhao and coworkers for the first time in 1998 [14]. The internal surface of SBA-15 can be functionalized with different organic functional groups [15-18] to produce an effective and active catalyst. It has exceptional advantages such as high surface area, large pore size and high thermal stability; in conclusion, it shows excellent catalytic activity in organic transformations [19-21]. In this paper, sulfonic acid functionalized silica (SBA-Pr-SO 3 H) was used as a heterogeneous Brønsted acid catalyst in the synthesis of 2,3-dihydroquinazolin-4(1H)-one derivatives. Then, in
2019
In this work, the SBA-15-supported dithizone-copper(I) [SBA-15-dtz–Cu(I)] complex as a new heterogeneous catalyst is prepared for the first time. The catalyst prepared is characterized by the FT-IR spectroscopy, SEM, and ICP techniques. This reusable heterogeneous catalyst can be used in the click reactions for the green and facile synthesis of 1,4-disubstituted 1,2,3-triazolesvia a one-pot three-component reaction of benzyl chloride derivatives, terminal alkynes, and sodium azide in the water at 60 °C. A synthetic technique offering numerous advantages including environmentally friendly, high-to-excellent reaction yields, operational simplicity, short reaction times, reusability of the catalyst, and lack of an organic solvent was developed.