Isothiocyanates in Heterocyclic Synthesis

New thiophene derivatives: chemoselective synthesis, antitumor effectiveness, structural characterization, DFT calculations, Hirshfeld surface, and Fukui function analysis

In this study, the chemoselective synthesis of two new thiophene derivatives is presented. The structure of newly synthesized thiophenes derivatives; ethyl 4-acetyl-3-phenyl-5-(phenylamino)thiophene-2-carboxylate (5) and ethyl (E)-4-(3-(dimethylamino)acryloyl)-3-phenyl-5-(phenylamino)thiophene-2-carboxylate (8) were established using different FTIR and NMR spectral analyses. Compound 8 was isolated as single crystal and its 3D structure was determined using X-ray crystallographic analysis. Possible intermolecular interactions that control the molecular packing of 8 were elucidated using Hirshfeld topology analysis. The O…H (13.7%), H…H (55.3%) and C…C (2.3%) intermolecular interactions are the most significant. Fukui functions showed that C4 in thiophene 5 and C3 in thiophene 8 are the most reactive atoms for nucleophilic attack, while N9 in thiophene 5 and C1 in thiophene 8 are the most reactive atoms for electrophilic attack. Antitumor activity of thiophene 5 was assessed and the results showed higher activity against HepG-2 (7.46 µg/mL) compared to the HCT 116 (12.60 µg/mL) cell line.

Isothiocyanates: happy-go-lucky reagents in organic synthesis

Owing to their unique structural features, isothiocyanates (ITCs) are a class of highly useful and inimitable reagents as the -NCS group serves both as electrophile and nucleophile in organic synthesis. ITCs share a rich legacy in organic, medicinal, and combinatorial chemistry. Compared to their oxygen equivalents, isocyanates, ITCs are easily available, less unpleasant, and somewhat less harmful to work with (mild conditions) which makes them happy-go-lucky reagents. Functionalized ITCs can finely tune the reactivity of the -NCS group and thus can be exploited in the late-stage functionalization processes. This review's primary aim is to outline ITC chemistry in the construction and derivatization of heterocycles through the lens of sustainability. For ease and brevity, the sections are divided based on reactive centers present in functionalized ITCs and modes of cyclisation. Scrutinizing their probable unexplored directions for future research studies is also addressed.

Recent Advances in the Synthesis of Isothiocyanates Using Elemental Sulfur

Isothiocyanates (ITCs) are biologically active molecules found in several natural products and pharmaceutical ingredients. Moreover, due to their high and versatile reactivity, they are widely used as intermediates in organic synthesis. This review considers the best practices for the synthesis of ITCs using elemental sulfur, highlighting recent developments. First, we summarize the in situ generation of thiocarbonyl surrogates followed by their transformation in the presence of primary amines leading to ITCs. Second, carbenes and amines afford isocyanides, and the further reaction of this species with sulfur readily generates ITCs under thermal, catalytic or basic conditions. Additionally, we also reveal that in the catalyst-free reaction of isocyanides and sulfur, two—until this time overlooked and not investigated—different mechanistic pathways exist.

A more sustainable isothiocyanate synthesis by amine catalyzed sulfurization of isocyanides with elemental sulfur

Isothiocyanates (ITCs) are typically prepared using amines and highly toxic reagents such as thiophosgene, its derivatives, or CS2. In this work, an investigation of a multicomponent reaction (MCR) using isocyanides, elemental sulfur and amines revealed that isocyanides can be converted to isothiocyanates using sulfur and catalytic amounts of amine bases, especially DBU (down to 2 mol%). This new catalytic reaction was optimized in terms of sustainability, especially considering benign solvents such as Cyrene™ or γ-butyrolactone (GBL) under moderate heating (40 °C). Purification by column chromatography was further optimized to generate less waste by maintaining high purity of the product. Thus, E-factors as low as 0.989 were achieved and the versatility of this straightforward procedure was shown by converting 20 different isocyanides under catalytic conditions, while obtaining moderate to high yields (34-95%).

Natural Bioactive Compounds As Protectors Of Mitochondrial Dysfunction In Cardiovascular Diseases And Aging

Diet, particularly the Mediterranean diet, has been considered as a protective factor against the development of cardiovascular diseases, the main cause of death in the world. Aging is one of the major risk factors for cardiovascular diseases, which have an oxidative pathophysiological component, being the mitochondria one of the key organelles in the regulation of oxidative stress. Certain natural bioactive compounds have the ability to regulate oxidative phosphorylation, the production of reactive oxygen species and the expression of mitochondrial proteins; but their efficacy within the mitochondrial physiopathology of cardiovascular diseases has not been clarified yet. The following review has the purpose of evaluating several natural compounds with evidence of mitochondrial effect in cardiovascular disease models, ascertaining the main cellular mechanisms and their potential use as functional foods for prevention of cardiovascular disease and healthy aging.

Utility of 3-(thiophen-2-yl)prop-2-enoyl isothiocyanate in heterocyclic synthesis

Convenient syntheses of quinazoline, benzothiazole, thiadiazole, imidazole, and thiourea derivatives starting from 3-(thiophen-2-yl)prop-2-enoyl isothiocyanate are described. The structures of the synthesized compounds are confirmed from their microanalytical and spectral data. Some of the products are examined for their antibacterial activity against Gram-positive and Gram-negative bacteria and fungi.

Utility of Lauroyl Isothiocyanate as a Scaffold in the Synthesis of Some Novel Pyrimidine Derivatives and Their Antimicrobial Assessment

The reaction of lauroyl isothiocyanate 1 with enaminonitrile derivative 2 furnished N-(6-cyano-3, 4-diphenylthieno[2,3-c]pyridazin-5-yl-carbamothioyl)dodecanamide 3, which was used as precursor for the synthesis of novel heterocyclic systems. Polyfunctional pyrimidine and fused pyrimidine derivatives were obtained by the cyclization of compound 3 under different basic conditions as well as its reactions with thiourea, o-aminothiophenol, hydrazine hydrate, phenyl hydrazine, ethyl phenyl acetate or ethyl benzoyl acetate. The structures of the new compounds were confirmed by microanalytical and spectral properties. The synthesised compounds were tested in-vitro for their antimicrobial activity and showed congruent results against most of the tested microorganisms compared to the standard drugs Gentamycin and Ketoconazol.

Uses of 2-(Thiophene-2-carbonylcarbamothioylthio)acetic Acid as a Good Synthon for Construction of Some New Thiazole and Annulated Thiazole Derivatives

The reaction of thiophene-2-carbonyl isothiocyanate 2 with thioglycolic acid gave 2-(thiophene-2-carbonylcarbamothioylthio)acetic acid 3. Compound 3 was subjected to some selected reactions with sulphuric acid as well as benzaldehyde, piperonal and isatin under different reaction conditions. The products obtained were new derivatives of thiazole and annulated thiazole derivatives bearing thiophene moiety in some cases. The structures of the new synthesized compounds were confirmed on the basis of their microanalytical and spectral properties. Some compounds were tested for their antimicrobial activity against six selected microorganisms using the standard antibacterial Gentamycin and antifungal Ketoconazole as references.

Synthesis, docking study and biological evaluation of some new thiourea derivatives bearing benzenesulfonamide moiety

Background

A series of novel N-(2, 6-dimethoxypyrimidin-4-yl)-4-(3-(aryl)thioureido) benzenesulfonamides 3a–t was synthesized by the addition of N-(2,6-dimethoxypyrimidin-4-yl)-4-isothiocyanatobenzenesulfonamide 2 to the appropriate aromatic amine. The structures of the synthesized compounds were inspired from the second line antituberculosis pro-drugs.

Results

Most of the new compounds were screened for their activity against Mycobacterium tuberculosis. The results of the antimycobacterial assay showed that compound 3i exerted the highest activity (MIC = 3.13 µg/mL), followed by compound 3s (MIC = 6.25 µg/mL).

Conclusion

The structure–activity relationship (SAR) analysis revealed that the introduction of the benzo[1,3]dioxol moiety in 3i and the 4-morpholinyl-4-phenyl moiety in 3s has proven to give the most potent compounds in this study. Docking of the promising compounds inside the active site of M. tuberculosis enoyl reductase InhA was performed in order to emphasize the results. The compounds showed a similar orientation to that of GSK 625 inside the active site of 5JFO and bind to Met 98 in a way similar to that of the co-crystallized ligand.

Antimicrobial and anticancer activity of some novel fluorinated thiourea derivatives carrying sulfonamide moieties: synthesis, biological evaluation and molecular docking

BACKGROUND

Various thiourea derivatives have been used as starting materials for compounds with better biological activities. Molecular modeling tools are used to explore their mechanism of action.

RESULTS

A new series of thioureas were synthesized. Fluorinated pyridine derivative 4a showed the highest antimicrobial activity (with MIC values ranged from 1.95 to 15.63 µg/mL). Interestingly, thiadiazole derivative 4c and coumarin derivative 4d exhibited selective antibacterial activities against Gram positive bacteria. Fluorinated pyridine derivative 4a was the most active against HepG2 with IC50 value of 4.8 μg/mL. Molecular docking was performed on the active site of MK-2 with good results.

CONCLUSION

Novel compounds were obtained with good anticancer and antibacterial activity especially fluorinated pyridine derivative 4a and molecular docking study suggest good activity as mitogen activated protein kinase-2 inhibitor. Graphical abstract Compound 4a in the active site of MK-2.

Use of Phthalimidoacetyl Isothiocyanate as a Scaffold in the Synthesis of Target Heterocyclic Systems, and Their Antimicrobial Assessment

Phthalimidoacetyl isothiocyanate underwent addition-cyclization reactions with some nitrogen and carbon nucleophilic reagents. Simultaneous or subsequent cyclization of the obtained adducts gave target heterocyclic systems such as 1,2,4-triazoles, 1,3-diazines, 1,3-oxazines and thiourea attached to a phthalimido moiety. The antimicrobial activity of the synthesized compounds was tested.

A Facile One-pot Synthesis and Heterocyclisation of (R)-2-amino-3-((aroylcarbamothioyl)thio)propanoic Acids

A series of ( R)-2-amino-3-((aroylcarbamothioyl)thio)propanoic acid derivatives have been synthesised by a one-pot, three-component reaction of L-cysteine with ammonium thiocyanate in the presence of various acid chlorides under solvent-free conditions in excellent yields. These compounds were converted to ( R)-2-thioxothiazolidine-4-carboxylic acid in water under reflux conditions.