I2/DMSO-catalyzed one-pot approach for the synthesis of 1,3,4-selenadiazoles

KI mediated one-pot cascade reaction for synthesis of 1,3,4-selenadiazoles

An efficient catalytic system consisting of KI and K2S2O8 for a one-pot pseudo three-component cascade reaction in the preparation of a diverse array of 1,3,4-selenadiazole derivatives from easily accessible precursors aldehydes, hydrazine and elemental selenium is demonstrated in this paper. Here, KI is used as the surrogate of iodine and K2S2O8 as the oxidant. The key advantages of this protocol include an easy reaction set up, operational simplicity, high functional group tolerance and utilisation of low toxicity chemicals. Further, a radical quenching reaction was also performed to confirm the mechanistic pathway.

I2/DMSO-mediated oxidative C-C and C-heteroatom bond formation: a sustainable approach to chemical synthesis

The I2/DMSO pair has emerged as a versatile, efficient, practical, and eco-friendly catalyst system, playing a significant role as a mild oxidative system, and thus employed as a good alternative to metal catalysts in synthetic chemistry. Presently, I2/DMSO is a thriving catalytic system that is used in preparing C-C and C-X (X = O/S/N/Se/Cl/Br) bonds, resulting in the formation of various bioactive molecules. Many processes utilize this system, including in situ glyoxal synthesis by diverse sp, sp2, and sp3 functionalities via iodination and subsequent Kornblum oxidation. Focusing on oxidation processes, this study examines the synergistic effect of dimethyl sulfoxide (DMSO) and molecular iodine in improving synthetic techniques. We provide a comprehensive overview of the research progress on the I2/DMSO catalytic system for the formation of C-C and C-heteroatom bonds from 2018 to the present. Additionally, the future prospects of this research field are discussed.

First Exclusive Stereo- and Regioselective Preparation of 5-Arylimino-1,3,4-Selenadiazole Derivatives: Synthesis, NMR analysis, and Computational Studies

Isoselenocyanates are valuable coupling partners required for preparing key chemical intermediates and biologically active molecules in an accelerated and effective way. Likewise, (Z)-2-oxo-N-phenylpropanehydrazonoyl chlorides have been employed in numerous one-step heteroannulation reactions to assemble the structural core of several various kinds of heterocyclic compounds. Here, we describe the inverse electron demand 1,3-dipolar cycloaddition reaction of isoselenocyanates with a variety of substituted (Z)-2-oxo-N-phenylpropanehydrazonoyl chlorides to generate, regioselectively and stereoselectively, a series of 5-arylimino-1,3,4-selenadiazole derivatives comprising a multitude of functional groups on both aryl rings. The synthetic method features gentle room-temperature conditions, wide substrate scope, and good to high reaction yields. The selenadiazoles were separated by gravity filtration in all instances and chemical structures were validated by multinuclear NMR spectroscopy and high accuracy mass spectral measurements. First conclusive molecular structure elucidation of the observed 5-arylimino-selenadiazole regioisomer was verified by single-crystal X-ray diffraction analysis. Crystal-structure measurement was successfully carried out on (Z)-1-(4-(4-iodophenyl)-5-(p-tolylimino)-4,5-dihydro-1,3,4-selenadiazol-2-yl)ethan-1-one and (Z)-1-(5-((4-methoxyphenyl)imino)-4-(4-(methylthio)phenyl)-4,5-dihydro-1,3,4-selenadiazol-2-yl)ethan-1-one. Likewise, the (Z)-geometry of the hydrazonoyl chloride reactant was proven by X-ray diffraction studies. As representative examples, crystal-structure determination was carried out on (Z)-2-oxo-N-phenylpropanehydrazonoyl chloride and (Z)-N-(3,5-bis(trifluoromethyl)phenyl)-2-oxopropanehydrazonoyl chloride. Density functional theory calculations at the B3LYP-D4/def2-TZVP level were conducted to support the noted experimental findings and suggested mechanism.

Design, synthesis and biological evaluation of novel deoxyvasicinone-indole as multi-target agents for Alzheimer's disease

In this study, a series of multifunctional hybrids (6a-6l) against Alzheimer's disease were designed and obtained by conjugating the pharmacophores of deoxyvasicinone and indole. These analogs of deoxyvasicinone-indole were evaluated as inhibitors of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE), and as inhibitors of amyloid aggregation (Aβ_1-42) for treatment of Alzheimer's disease (AD). Subsequently, AChE induced Aβ aggregation inhibition test was also performed for selected compounds. Biological activity results demonstrated that compound 6b was the most potent and balanced dual ChEs inhibitor with IC₅₀ values 0.12 µM and 0.15 µM for eeAChE and eqBuChE, respectively. Kinetic analysis and docking study indicated that compound 6b was a mixed-type inhibitor for both AChE and BuChE. Compound 6b also found to be the best inhibitors of self-induced Aβ_1-42 aggregation with IC₅₀ values of 1.21 µM. Compound 6b also afforded excellent inhibition of AChE-induced Aβ_1-42 aggregation by 81.1%. Overall, these results indicate that 6b may be considered as lead compound for the development of highly effective anti-AD drugs.