Immobilized Sulfuric Acid on Silica Gel as Highly Efficient and Heterogeneous Catalyst for the One-Pot Synthesis of Novel α-Acyloxycarboxamides in Aqueous Media.

The application of immobilized sulfuric acid on silica gel (H2SO4-SiO2) as an efficient and easily reusable solid catalyst was explored in the synthesis of novel α-acyloxycarboxamide derivatives via a Passerini reaction of benzoic acid, aldehyde/ketone, and isocyanides. The Passerini adducts were obtained in high to excellent yields within 10 min in aqueous media under catalytic conditions. The key advantages of the process include a short reaction time, high yields, the catalyst's low cost, and the catalyst's reusability.

Synthesis and biological evaluation of bis-N2,N2'-(4-hydroxycoumarin-3-yl)ethylidene]-2,3-dihydroxysuccinodihydrazides.

A series of N2,N2'-bis[4-hydroxycoumarin-3-yl)ethylidene]-2,3-dihydroxysuccino-hydrazides, containing 4-hydroxycoumarin, hydrazine and tartaric acid moieties, have been prepared and examined for possible biological activity. Several of these compounds exhibit promising HIV-1 integrase inhibition (IC50 = 3.5 µM), and anti-T. brucei (32% viability) and anti-mycobacterial (Visual MIC90 = 15.63 µM) activity.

Exploring intermolecular contacts in multi-substituted benzaldehyde derivatives: X-ray, Hirshfeld surface and lattice energy analyses.

Crystal structures of six benzaldehyde derivatives (1-6) have been determined and their supramolecular networks were established by an X-ray crystallographic study. The study has shown that the compounds are linked by various intermolecular interactions such as weak C-H⋯O hydrogen bonding, and C-H⋯π, π-π and halogen bonding interactions which consolidate and strengthen the formation of these molecular assemblies. The carbonyl group generates diverse synthons in 1-6via intermolecular C-H⋯O hydrogen bonds. An interplay of C-H⋯O hydrogen bonds, and C-H⋯π and π-π stacking interactions facilitates the formation of multi-dimensional supramolecular networks. Crystal packings in 4 and 5 are further generated by type I halogen⋯halogen bonding interactions. The differences in crystal packing are represented by variation of substitution positions in the compounds. Structure 3 is isomorphous with 4 but there are subtle differences in their crystal packing. The nature of intermolecular contacts in the structures has been studied through the Hirshfeld surfaces and two-dimensional fingerprint plots which serve as a comparison in constructing different supramolecular networks. The intermolecular interaction energies are quantified utilizing theorectical calculations for the title compounds and various analogous structures retrieved from the Cambridge Structural Database (CSD). Also intermolecular interactions for the molecular pairs are exctrated from respective crystal structures. Essentially, there are some invariant and variable intermolecular contacts realized between different groups in all six structures. The ab initio DFT total lattice energy (E Tot) calculations showed a direct correlation with thermal strengths of the title compounds.

Synthesis and evaluation of 3-hydroxy-3-phenylpropanoate ester­AZT conjugates as potential dual-action HIV-1 Integrase and Reverse Transcriptase inhibitors.

Novel 3-hydroxy-3-phenylpropanoate ester-azidothymidine (AZT) conjugates have been prepared using Baylis-Hillman methodology, and their potential as dual-action HIV-1 Integrase and Reverse Transcriptase inhibitors has been explored using enzyme inhibition and computer modelling techniques; their activity and HeLa cell toxicity have been compared with those of their cinnamate ester analogues.