Microwave‐assisted Synthesis of Novel 3,4‐Bis‐chalcone‐N‐arylpyrazoles and Their Anti‐inflammatory Activity

A series of 3,4‐bis‐chalcone‐N‐arylpyrazoles 3a‐h was prepared conveniently from diacetyl pyrazoles 2a,b . All reactions were carried out under conventional thermal heating and/or microwave irradiation. The structure of the latter functionally pyrazoles was confirmed under the bases of their IR, mass, ¹H NMR and ¹³C NMR. The X‐ray diffraction of compound 3e not only confirmed the chemical structure of 3a‐h , but also showed the E configuration of their chalcone moieties. Treatment of compound 3e with phenyl hydrazine in presence of acetic acid afforded the tri‐pyrazle 4 . The anti‐inflammatory activity of the newly synthesized compounds was investigated. Some of these compounds showed a moderate activity when compared with indomethacin as a reference drug. The combination between chalcone and pyrazole moieties revealed a variable effect in anti‐inflammatory activity.     

β‐Polynitration of 5,10,15,20‐tetrakis(2′,6′‐Dichlorophenyl)porphyrins with HNO3 and Cu(NO3)2 on Clay Using Microwave Irradiation

Abstract

An expeditious β‐polynitration of 5,10,15,20‐tetrakis(2′,6′‐dichlorophenyl)porphyrin, its Zn and Cu derivatives with montmorillonite K10‐HNO₃ and montmorillonite K10‐Cu(NO₃)₂ (claycop) under mild conditions using microwave irradiation in 72–95% yields has been described.     

A Stereoselective Route to (E)-Vinylic Selenides through the Palladium-Catalyzed Cross-Coupling Reaction of Selenovinylicdialkylboranes with Alkyl Halides

The reaction of selenoviylicdialkyboranes with alkyl halides takes place readily in the presence of Pd(PPh₃)₄ and sodium methoxide to afford (E)-vinylic selenides in excellent yields     

Conventional and Microwave Assisted Hydrogenolysis Using Zinc and Ammonium Formate

Abstract

The selective deprotection of several N‐Bzl amino derivatives to the corresponding amines and the removal of S‐Bzl and O‐Bzl groups from the protected amino acids with ammonium formate and commercial zinc dust are reported. Many other reducible or hydrogenolysable substituents such as halogens, methoxy, phenol, ester, acid, ethene, and Boc groups are unaffected.     

Increasing appendage diversity on 3,4-dihydro-3-oxo-2H-1,4-benzoxazines via Aphos–Pd(OAc)2-catalyzed Suzuki–Miyaura cross-coupling of aryl chlorides

A library of 32 members of 3,4-dihydro-3-oxo-2H-1,4-benzoxazines has been synthesized from two substituted 2-aminophenols via microwave-assisted one-pot regioselective annulation of 2-bromoalkanoates and subsequent Suzuki–Miyaura cross-coupling of the chloro-substituted scaffolds. The latter transformation was carried out using our Aphos–Pd(OAc)₂ catalyst and the coupling of the aryl chlorides with arylboronic acids proceeded under mild reaction conditions at 60–80 °C in THF–H₂O (10:1) in the presence of K₃PO₄·3H₂O as the base to furnish the corresponding biaryl products in 80–98% yields.     

On DABAL-Me3 promoted formation of amides

The range and utility of DABAL-Me₃ couplings of methyl esters and free carboxylic acids with primary and secondary amines under a variety of conditions (reflux, sealed tube, microwave) has been compared for a significant range of coupling partners of relevance to the preparation of amides of interest in pharmaceutical chemistry. Commercial microwave reactors promote the fastest couplings and allow the use of significantly sterically hindered amines (primary and secondary) and carboxylic acids derivatives. The influence of microwave energy on the reaction system was shown to be typically related to thermal effects (over-pressuring and superheating).     

One-Pot Synthesis of Salicylanilides by Direct Amide Bond Formation from Salicyclic Acid Under Microwave Irradiation

A highly efficient protocol for the preparation of aromatic amides is described by the direct reactions between salicyclic acid and aromatic amines in the presence of phosphorous trichloride under microwave irradiation. The method has several advantages over the conventional methods, including operational simplicity, good yield, and reduced reaction time.

A concise synthesis of indoloquinoline skeletons applying two consecutive Pd-catalyzed reactions

The indoloquinoline alkaloids cryptolepine (1), neocryptolepine (2), isocryptolepine (3), and isoneocryptolepine (4) are important tools in traditional medicine. Now, their precursors 1a–4a were synthesized in two steps starting from the corresponding bromo-iodoquinolines. Our strategy is based on palladium-catalyzed reactions, applying regioselective Buchwald–Hartwig amination on 2,3- and 3,4-dihaloquinolines followed by an intramolecular Heck-type reaction. Both steps were carried out under microwave irradiation.     

A facile and rapid access towards the synthesis of 2,3-dihydroquinazolin-4(1H)-ones

An efficient synthetic route for 2,3-dihydroquinazolin-4(1H)-ones using 2-morpholinoethanesulfonic acid as a potential and new organocatalyst is described. The developed synthetic protocol represents a novel and very simple route for the preparation of 2,3-dihydroquinazolin-4(1H)-one derivatives. In addition, microwave irradiation technique is successfully implemented for carrying out the reactions in shorter reaction times.     

An alternative synthetic approach for the synthesis of biologically relevant 1,4-disubstituted pyrazolo[3,4-d]pyrimidines

A versatile approach for the synthesis of 1,4-disubstituted pyrazolo[3,4-d]pyrimidines has been developed. Starting from commercially available allopurinol, TBAF mediated N1-functionalization and subsequent C4 nucleophilic substitution, under microwave assisted- or standard heating conditions, granted access to highly functionalized pyrazolo[3,4-d]pyrimidines of potential biological interest.