Ultrasound-assisted one-pot three-component synthesis of new isoxazolines bearing sulfonamides and their evaluation against hematological malignancies.

In the present study, following a one-pot two-step protocol, we have synthesized novel sulfonamides-isoxazolines hybrids (3a-r) via a highly regioselective 1,3-dipolar cycloaddition. The present methodology capitalized on trichloroisocyanuric acid (TCCA) as a safe and ecological oxidant and chlorinating agent for the in-situ conversion of aldehydes to nitrile oxides in the presence of hydroxylamine hydrochloride, under ultrasound activation. These nitrile oxides could be engaged in 1,3-dipolar cycloaddition reactions with various alkene to afford the targeted sulfonamides-isoxazolines hybrids (3a-r). The latter were assessed for their antineoplastic activity against model leukemia cell lines (Chronic Myeloid Leukemia, K562 and Promyelocytic Leukemia, HL-60).

Ultrasound-assisted one-pot green synthesis of new N- substituted-5-arylidene-thiazolidine-2,4-dione-isoxazoline derivatives using NaCl/Oxone/Na3PO4 in aqueous media.

A rapid and green method for the synthesis of novel N-thiazolidine-2,4-dione isoxazoline derivatives 5 from N-allyl-5-arylidenethiazolidine-2,4-diones 3 as dipolarophiles with arylnitrile oxides via 1,3-dipolar cycloaddition reaction. The corresponding N-allyl substituted dipolarophiles were prepared by one-pot method from thiazolidine-2,4-dione with aldehydes using Knoevenagel condensation followed by N-allylation of thiazolidine-2,4-dione in NaOH aqueous solution under sonication. In addition, the isoxazoline derivatives 5 were synthesized by regioselective and chemoselective 1,3-dipolar cycloaddition using inexpensive and mild NaCl/Oxone/Na3PO4 as a Cl source, oxidant and/or catalyst under ultrasonic irradiation in EtOH/H2O (v/v, 2:1) as green solvent. All synthesized products are furnished in good yields in the short reaction time, and then their structures were confirmed by NMR, mass spectrometry and X-ray crystallography analysis.

Concise synthesis and antibacterial evaluation of novel 3-(1,4-disubstituted-1,2,3-triazolyl)uridine nucleosides.

We report herein a simple and efficient synthesis of a new series of antibacterial uridine nucleosides. The strategy involved a sequential silylation/N-glycosylation/N-propargylation procedure of uracil 1 for preparing the dipolarophile 5 in good yield. A series of novel uridine-[1,2,3]triazole nucleosides 6a-j were efficiently synthesized via the copper-catalyzed azide-alkyne cycloaddition (CuAAC) from dipolarophile 5 with different selected azides. The reactions were carried out under both conventional and ultrasonic irradiation conditions. In general, improvements were observed when reactions were carried out under sonication. Their antibacterial potential has been evaluated by means of a micro-dilution assay against either Gram-positive or Gram-negative bacteria. Compounds 6i and 6j have shown significant bactericidal activity against Staphylococcus aureus (MIC = 10 and 6 µM, respectively), and 6h against Escherichia coli (MIC = 8 µM). Moreover, antibacterial kinetic assays showed that 6i and 6j significantly reduced the S. aureus growth rate at the MIC concentration, after 6 h, compared to their deprotected analogs, 6k and 6l, respectively. Compound 6h also significantly reduced the growth of E. coli. These antibacterial effects may be related to the penetrating properties of these compounds, as revealed by the leakage of nucleic acids from the sensitive strains.