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The diisopropyl ethyl ammonium acetate (DIPEAc)-promoted Biginelli protocol has been developed for the first time by a successive one-pot three-component reaction of aldehydes, ethylcyanoacetate/ethyl acetoacetate, and thiourea/urea to afford pharmacologically promising 1,2,3,4-tetrahydropyrimidines in high yields at room temperature. The key benefits of the present scheme are the capability to allow a variability of functional groups, short reaction times, easy workup, high yields, recyclability of the catalyst, and solvent-free conditions, thus providing economic and environmental advantages. In addition, a series of 4-oxo-6-aryl-2-thioxo-1,2,3,4-tetrahydropyrimidine-5-carbonitriles analogues were synthesized and selected for their in vitro antifungal and antibacterial activities.

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Disubstituted oxazol-5-one and pyrazoles are known to exhibit various biological activities. Therefore, in this work, we designed pyrazole containing 2,4-disubstituted oxazol-5-one (3a-g) as a new class of antimicrobial agents. Synthesis of titled compounds was carried out by two different methods. In the first method (conventional Method A), disubstituted oxazol-5-one (3a-g) was prepared by reacting 1-phenyl-3-p-tolyl-1Hpyrazole-4-carbaldehyde (1a-g) with hippuric acid (2) and sodium acetate, in an acetic anhydride for 2.5 -4 h. In the second method (Method B), the above reaction was carried out under microwave assistance. Compared to the conventional method, the microwave-assisted synthesis of 3,4,5-trisubstituted imidazoles demonstrate several advantages, in terms of reaction time and overall yield. All the test compounds were evaluated for in vitro antibacterial and antifungal activities. In general, compounds with electron withdrawing groups showed good antibacterial and antifungal activities. Among the compound tested, compound (3d) showed highest activity.

A one pot, three-component condensation of benzoin/benzyl, an aldehyde, and ammonium acetate using diethyl bromophosphate as a mild oxidant is achieved to form trisubstituted imidazole compounds. Under ultrasound irradiation, a smooth condensation occurs to get the 2, 4, 5-triaryl-1H-imidazole compounds in good to excellent yields. The study explores the scope and limitation of diethyl bromophosphate as an oxidant and suggests advantages, viz., simplicity of operation, reduction in time, and an increase in product yields.

An efficient synthesis of 1,5-Benzothiazepines via Michael addition of corresponding (E)-1-(2-hydroxyphenyl)-3-(4-(phenylthio)phenyl)prop-2-en-1-one is described under ultrasound irradiation. A series of novel 2-((E)-2,3-dihydro-2-(4-(phenylthio)phenyl)benzo [b][1,4]thiazepin-4-yl)phenol derivatives was confirmed on the basis of 1 H NMR, Mass, IR spectral data and Elemental analysis. The synthesized compounds were evaluated for their antimicrobial activities. Most of the compounds were found to be comparable potent than the reference standard drugs. Utilization of ultrasound irradiation, simple reaction conditions, isolation, and purification makes this manipulation very interesting from an economic and environmental perspective.

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