A simple green synthesis of (Z)-5-arylmethylene-4- thioxothiazolidines and thiopyrano[2,3-d]thiazolidine-2-thiones in PEG-400 under catalyst-free conditions

Molecular design, synthesis and anticancer activity of new thiopyrano[2,3-d]thiazoles based on 5-hydroxy-1,4-naphthoquinone (juglone)

A series of 11-substituted 9-hydroxy-3,5,10,11-tetrahydro-2H-benzo[6,7]thiochromeno[2,3-d][1,3]thiazole-2,5,10-triones 3.1-3.13 were synthesized via hetero-Diels-Alder reaction of 5-ene-4-thioxo-2-thiazolidinones and 5-hydroxy-1,4-naphthoquinone (juglone). The structure of newly synthesized compounds was established by means of spectral data and a single-crystal X-ray diffraction analysis. The synthesized compounds were tested on a panel of cell lines representing different types of cancer as well as normal and pseudonormal cells and peripheral human blood lymphocytes. Compound 3.10 was found to be the most active derivative, exhibiting a cytotoxic effect similar to doxorubicin's one (IC₅₀ ranged from 0.6 to 5.98 μM), but less toxic to normal and pseudonormal cells. All synthesized compounds were able to interact with DNA, although their anticancer activity did not correlate with the potency of interaction with DNA. The status of p53 in colorectal cancer cells correlated with the activity of the synthesized derivatives 3.1, 3.7, and 3.10. Compound 3.10 did not have an acute toxic effect on the body of С57BL/6 mice, unlike the well-known anticancer drug doxorubicin, which was used as a positive control. The injection of 3.10 (20 mg/kg) to mice had no effect on the counts of leukocytes, erythrocytes, platelets and hemoglobin level in their blood, in contrast to doxorubicin, which caused anemia and leukopenia, indicating bio-tolerance of 3.10in vivo.

Exploring the Relationship between Reactivity and Electronic Structure in Isorhodanine Derivatives Using Computer Simulations

The electronic structure and reactivity of 22 isorhodanine (IsRd) derivatives in the Diels-Alder reaction with dimethyl maleate (DMm) were investigated under two different environments (gas phase and continuous solvent CH3COOH), using free Gibbs activation energy, free Gibbs reaction energy, and frontier molecular orbitals to analyze their reactivity. The results revealed both inverse electronic demand (IED) and normal electronic demand (NED) characteristics in the Diels-Alder reaction and also provided insights into the aromaticity of the IsRd ring by employing HOMA values. Additionally, the electronic structure of the IsRd core was analyzed through topological examination of the electron density and electron localization function (ELF). Specifically, the study demonstrated that ELF was able to successfully capture chemical reactivity, highlighting the potential of this method to provide valuable insights into the electronic structure and reactivity of molecules.

Thiopyrano[2,3-d]Thiazoles as New Efficient Scaffolds in Medicinal Chemistry

This review presents the up to date development of fused thiopyranothiazoles that comprise one of the thiazolidine derivatives classes. Thiazolidine and thiazolidinone-related compounds belong to the widely studied heterocycles from a medicinal chemistry perspective. From the chemical point of view, they are perfect heterodienes to undergo hetero-Diels–Alder reaction with a variety of dienophiles, yielding regio- and diastereoselectively thiopyranothiazole scaffolds. The annealing of thiazole and thiopyran cycles in condensed heterosystem is a precondition for the “centers conservative” creation of the ligand-target binding complex and can promote a potential selectivity to biotargets. The review covers possible therapeutic applications of thiopyrano[2,3-d]thiazoles, such as anti-inflammatory, antibacterial, anticancer as well as aniparasitic activities. Thus, thiopyrano[2,3-d]thiazoles may be used as powerful tools in the development of biologically active agents and drug-like molecules.

Tandem hetero-Diels–Alder-hemiacetal reaction in the synthesis of new chromeno[4′,3′:4,5]thiopyrano[2,3-d]thiazoles

Novel rel-(5aR,6R,11bS)-6-hydroxy-3,5a,6,11b-tetrahydro-2H,5H-chromeno[4′,3′:4,5]thiopyrano[2,3-d][1,3]thiazole-2-ones were synthesized via tandem hetero-Diels-Alder-hemiacetal reaction of 5-(2-hydroxybenzylidene)-4-thioxo-2-thiazolidinones and α,β-unsaturated aldehydes. The stereochemistry of cycloadditions was confirmed by NMR spectra and a single crystal X-ray diffraction analysis.

Sequential Diels–Alder Reactions in a Conjugated Tetraene System

A sequence of two Diels–Alder reactions is observed for the reaction of bis-diene ( E)-3-[2-(furan-2-yl)vinyl]-5,5-dimethylcyclohex-2-en-1-one with two equivalents of N-phenylmaleimide. This study shows that the electron-deficient furanyl site, which is primarily “inactive” towards a [4 + 2] reaction, easily undergoes cycloaddition with the second equivalent of N-phenylmaleimide to produce the final bis-adduct. This is because the first Diels–Alder reaction between N-phenylmaleimide and the more reactive cyclohex-2-en-1-one site of the diene converts the 2-furanyl ring to a more electron-rich component, since the electron-withdrawing double bond attached to the furan ring changes to an electron-releasing alkyl group after the first cycloaddition. Consequently, the resulting furanyl diene is then able to undergo the second cycloaddition.