Joice Thomas

• PhD
• PostDoc Position at KU Leuven

The present review narrates several reports which deal with the synthesis of fused 1,2,3-triazole containing scaffolds following a sequential multicomponent reaction (MCR)-intramolecu-lar azide-alkyne cycloaddition (IAAC) approach. The reviewed reactions were cleverly designed so as to incorporate azide and alkyne functionalities in the MCR product...

The preparation of a series of novel homochiral atropisomeric sulfanyl- and sulfoxide-substituted naphthyltriazoles is described. The triazolization methodology used presents a new way towards novel and highly stable 1,2,3-triazole-based atropisomers, and introduces a new and complementary synthetic pathway towards 4-sulfanyl substituted 1,2,3-tria...

In recent decades, considerable research attention has been devoted to new synthetic procedures for thiacyclophanes. Thiacyclo-phanes are widely used as host molecules for the molecular recognition of organic compounds as well as metals. Herein, we report the selective and high-yielding synthesis of novel alternate-linked-meta-para-thiacyclophanes....

An easily upscalable synthesis method for 1,2,3‐triazolium ionic liquids is presented. Several ionic liquids were synthesized and characterized. The influence of the side chain structure on the base‐stability was investigated. One example, functionalized with linear alkyl side chains, was found to exhibit excellent stability against hot concentrate...

A practical and strightforward approach that enables for the first time, the synthesis of enantiomerically pure 1,4,5- trisubstituted, 1,5-disubstituted, and fused 1,2,3 triazoles derivatives has been developed. The synthesis employs enantiomerically pure amino esters derived from amino acids and commercially available ketones under metla-free cond...

A practical and straightforward approach that enables for the first time, the synthesis of enantiomerically pure 1,4,5-trisubstituted, 1,5-disubstituted, and fused 1,2,3 triazole derivatives has been developed. The synthesis employs enantiomerically...

A practical three-step protocol for the assembly of triazolobenzodiazepine-fused diketopiperazines and hydantoins has been developed. The synthesis of these tetracyclic ring systems was initiated by an Ugi reaction, which brought together all necessary func-tionalities for further transformations. The Ugi adducts were then subjected to a base-induc...

Current chemotherapy regimens often include non-specific cytostatic/cytotoxic drugs, which do not distinguish between normal and tumor cells, therefore causing considerable systemic toxicity. We previously reported the synthesis and antiproliferative activity of a novel synthetic 2-aminothiophene-3-carboxylic acid ester derivative TJ191 that select...

Three series of aza-artemisinin derivatives were synthesized for studies of anticancer activity. The first series of compounds were prepared via copper(I)-catalyzed azide alkyne cycloaddition, so called “click reaction”, starting from propargyl derivatives of 11-aza-artemisinin and various azides, whereas the second and third series of compounds we...

Selective reductive catalytic depolymerisation of softwood lignin (e.g. pine, spruce) yields predominantly 4-n-propylguaiacol (4PG; 15-20 wt% on lignin basis), an interesting platform chemical for bio-based chemistry. This contribution specifically shows promising technical, sustainable and environmental advantages of such bio-phenol for various po...

The Gewald three-component reaction yielding highly substituted 2-aminothiophene heterocycles has been known for a long time and holds an extraordinary potential in pharmaceutical industry. Herein, we describe a four-component reaction initiated by the conjugate addition of different indole derivatives to α, β-unsaturated carbonyl compounds. This i...

Novel 1,2,3-triazolium ionic liquids with a high base stability were synthesized for use in solvent extraction of first-row transition elements and rare earths from chloride media. The synthesis of these ionic liquids makes use of a recently reported, metal-free multicomponent reaction that allows full substitution of the 1,2,3-triazolium skeleton....

Artemisinin and synthetic derivatives of dihydroartemisinin are known to possess various biological activities. Post-functionalization of dihydroartemisinin with triazole heterocycles has been proven to lead to enhanced therapeutic potential. By using our newly developed triazolization strategy, a library of unexplored fused and 1,5-disubstituted 1...

The layer-by-layer method is an attractive technique for the fabrication of ultrathin nanostructured polyelectrolyte multilayer membranes (PEMM). A simple two-step procedure is described here for the preparation of an ultrathin, nanostructured membrane comprising a 5-7 nm thick selective layer, consisting only of one single bilayer of poly(diallyld...

5-(2-(4-Methoxyphenyl)ethyl)-2-amino-3-methylcarboxylate thiophene (TR560) is the prototype drug of a recently discovered novel class of tumor-selective compounds that preferentially inhibit the proliferation of specific tumor cell types (e.g. leukemia/lymphoma). Here, we further increased tumor selectivity by simplification of the molecule through...

A novel palladium-catalyzed direct C(sp³)-H arylation of the methyl group at the 8-position of BODIPY by bromoarenes was established. A deprotonative cross-coupling process is supposed to be involved in the reaction. This approach allowed us to attach electron donating/withdrawing, halogen substituted aryls and a heteroaryl with a yield running fro...

A practical, straightforward, and highly regioselective Zn(OAc)2 mediated method towards propargyl triazoles has been developed for the first time from commercially available enolizable ketones and propargyl amine. Post functionalization of this triazole leads to unique N,C-linked bis-triazoles in excellent yield.

Starting from a variety of compounds having activated methyl groups, such as ketones, a straightforward method for the synthesis of 1,4-disubstituted 1,2,3-triazoles is developed.

The expanded analogs of the calix[n]arenes in which the aryl units are (meta) connected via a polyatomic rather than a CH2 or heteroatom bridge can be called homocalix[n]arenes, and more particularly homoheteracalix[n]arenes if at least one heteroatom is part of the bridge. The first examples of systems with sulfur heteroatoms were reported in the...

NH-1,2,3-triazole moieties are a part of the design of various biologically active compounds, pharmaceutical agents and functional materials. Unfortunately, the applications of this heterocycle are still underexplored due to the lack of a general synthetic protocol. Here we outline a novel, general and facile metal-free pathway that enables the dir...

An unprecedented selective preparation of 1,5-disubstituted 1,2,3-triazoles from readily available primary amines, enolizable ketones and 4-nitrophenyl azide as a renewable source of dinitrogen is developed.

Functionalized 1,2,3-triazole heterocycles have been known for a long time and hold an extraordinary potential in diverse research areas ranging from medicinal chemistry to material science. However, the scope of therapeutically important 1-substituted 4-acyl-1H-1,2,3-triazoles is much less explored, probably due to the lack of synthetic methodolog...

An unprecedented approach that enables the direct and selective preparation of 1,5-disubstituted 1,2,3-triazoles from abundantly available building blocks such as primary amines, enolizable ketones and 4-nitrophenyl azide as a renewable source of dinitrogen via an organocascade process has been developed. Furthermore, this efficient methodology als...

The present invention relates to compounds having cytostatic activity against tumor cells. The compounds of the invention are of formula (I), or derivatives hereof, wherein R0, R1, R2, A, and X have defined meanings as described in claim 1.

A synthetic route towards homodiselenacalix[4]arene macrocycles is presented, based on the dynamic covalent chemistry of diselenides. The calixarene inner rim is decorated with either alkoxy or tert-butyl ester groups. Single-crystal X-ray analysis of two THF solvates with methoxy and ethoxy substituents reveals the high similarity of their molecul...

This contribution is about the design and synthesis of various sulfonated hyperbranched poly(arylene oxindole)s (SHPAOs) with different substituents via a convenient A2 + B3 polycondensation and subsequent sulfonation as water-soluble and recyclable acid catalysts for the conversion of cellulose to levulinic acid (LA). Whereas their molecular weigh...

The reactions of N-unsubstituted triazoles with sulfonyl chlorides afforded mixtures of regioisomeric 1- and 2-sulfonyl-1,2,3-triazoles. In some cases, pure regioisomers were obtained by crystallization of mixtures of isomers. 1,2,3-Triazoles bearing thiadiazole, isoxazole and benzene rings react with mesyl chloride and tosyl chloride to form mainl...

Facile synthesis of fused 1,2,3-triazoles by a proline-catalyzed reaction of an azido aldehyde and a nitroalkane is elaborated. The present tandem protocol proceeds via an organocatalytic Knoevenagel condensation of the azido aldehyde and nitroalkane followed by intramolecular azide–nitroalkene cycloaddition. The functionalized bicyclic triazole is...

The present feature article describes the different organocatalytic routes for the synthesis of substituted 1,2,3-triazoles. This methodology has recently gained much attention due to many advantages like high regioselectivity, substrate scope, high yields, and access to novel molecules. The review is divided into 4 different sections based on the...

A metal-free three-component reaction to synthesize 1,4,5-trisubstituted 1,2,3-triazoles from readily available building blocks, such as aldehydes, nitroalkanes, and organic azides, is described. The process is enabled by an organocatalyzed Knoevenagel condensation of the formyl group with the nitro compound, which is followed by the 1,3-dipolar cy...

In the present study carbazole based diaza[6]helicenes were synthesized utilizing the versatile quinoline and 9-(2-ethylhexyl)-2,7-dimethoxycarbazole-3-carbaldehyde building blocks, via the Wittig reaction-photocyclization strategy. The presence of bifunctional units comprising of electrophilic chloroquinoline and electron rich carbazole has opened...

In the present study, carbazole-based diaza[6]helicenes were synthesized utilizing versatile quinoline and 9-(2-ethylhexyl)-2,7-dimethoxycarbazole-3-carbaldehyde building blocks via the Wittig reactionphotocyclization strategy. The presence of bifunctional units comprising electrophilic chloroquinoline and electron-rich carbazole has opened up new...

Methyl-2-amino-5-[2-(4-methoxyphenethyl)]thiophene-3-carboxylate (8 c) is the prototype of a well-defined class of tumor-selective agents. Compound 8 c preferentially inhibited the proliferation of a number of tumor cell lines including many human T-lymphoma/leukemia cells, but also several prostate, renal, central nervous system and liver tumor ce...

Eine Mehrkomponentenreaktion für die Synthese von hoch funktionalisierten 1,4,5-trisubstituierten 1,2,3-Triazolen ausgehend von leicht zugänglichen Ausgangsverbindungen wie Aldehyden, Nitroalkanen und organischen Aziden beschreiben W. Dehaen et al. in ihrer Zuschrift auf S. 10319 ff. Die Statue “Fonske” oder “Fons Sapientiae” (Latein für “Quelle de...

A new class of pyrazolo[3,4-c]pyridine-3,7-dione and pyrazolo[3,4-d]azepine-3,7-dione scaffolds was synthesized via a Michael addition and reductive cyclization strategy. These fused heterocycles were accessed from simple starting materials like nitroolefins and 3-ethoxycarbonyl(methylene) pyrazoline-5-one. The pyrazolo fused heterocycles were obta...

The role of hydrotropic counteranions in governing the self-assembled structures of cationic bolaamphiphiles is studied in this work. We reveal that the ability of a hydrotropic counteranion to induce the formation of two-dimensional (2D) planar aggregates depends weakly on its polar head, but is strongly correlated to the size and the substituted...

2,3-Pentanedione (2,3-PD), a bio-based chemical derived from lactic acid, has the potential to serve as a precursor for the synthesis of novel bisphenols. We developed a solvent-free catalytic strategy for the condensation of phenol with 2,3-PD by using acid catalysts at temperatures ranging from 323 to 373 K. Various soluble and solid acids exhibi...

Synthetic procedures towards homodithiacalix[n]arenes are developed, starting from simple and readily available bifunctional aryl building blocks, by a dynamic covalent chemistry approach. Reaction of 1,3-bis(mercaptomethyl)-5-tert-butyl-2-methoxybenzene under basic conditions leads to a mixture of trimeric, tetrameric and pentameric dimethylenedit...

doi: 10.1080/10610278.2013.868898

In a previous study, we uncovered the anticonvulsant properties of turmeric oil and its sesquiterpenoids (ar-turmerone, α-, β-turmerone and α-atlantone) in both zebrafish and mouse models of chemically-induced seizures using pentylenetetrazole (PTZ). In this follow-up study, we aimed at evaluating the anticonvulsant activity of ar-turmerone further...

Frozen but flexible: The conformational flexibility of calixarene molecules is not only limited to solution. It can also manifest itself in single crystals as a response to the right external stimuli.

Disulfide bridged pillararene-like macrocycles were synthesized starting from 1,4-dialkoxybenzene and sulfur monochloride. The structure was determined using X-ray diffraction analysis.

Cytostatic agents often do not discriminate in their cytostatic potential between different tumor cell types in vitro. In this study, several 2-aminothiophene-3-carboxylic acid ester derivatives were discovered that show an unusual cytostatic selectivity for several T-cell (but not B-cell) lymphoma, prostate cancer, kidney carcinoma and hepatoma ce...

Selenacalix[3]triazines, cyclotrimeric metacyclophanes with direct Se linkages between the heteroaryl constituents, were shown to associate with various guest species. The preorganization of three electron deficient triazine rings allows for anions to bind through anion-π interactions, and alignment of the central nitrogen lone pairs and the well-d...

Selenium-bridged heteracalixarenes were synthesized by convenient one-pot SNAr reactions starting from variously 2-substituted 4,6-dichloro-1,3,5-triazine building blocks. Reactions of these precursors with sodium hydroselenide afforded the selenacalix[3]triazines as the only macrocyclic products. Yields of the cyclotrimers were significantly incre...

A series of novel hyperbranched polyselenides and polytellurides with multiple catalytic sites at the branching units has been synthesized via the polycondensation of A(2) + B(3) monomers. The GPx-like activities of these polymer mimics were assessed and it was found that the polytellurides showed higher GPx-like activities than the corresponding p...

The mechanism of the acid-catalyzed condensation between levulinic acid and phenol to form diphenolic acid (DPA) was investigated using a combination of sulfonated hyperbranched poly(arylene oxindole)s and thiols. Taft-type steric and electronic parameters were applied to study the correlation between the nature of the thiols and the condensation r...

A novel class of two atom bridged metacyclophanes-[2(4)]thiacalix[2]arene[2]pyrimidines-has been synthesized via a straightforward S(N)Ar reaction. The conformational properties and intra-annular dimensions of the [2(4)]thiacalix[2]arene[2]pyrimidines were evaluated by X-ray structure analysis and compared with known homothia- and thiacalixarenes....

Homoselenacalix[4]arenes were synthesized by a [2 + 2] reductive coupling protocol favouring the cyclotetramers. The inner and outer-rim decoration was varied and a bicyclic derivative was prepared by a similar one-pot procedure. Conformational analysis in solution and the solid state showed noticeable differences between the homoselenacalix[4]aren...

The trimeric macrocycles (II), obtained via nucleophilic aromatic substitution of halogenated triazines in a convenient one-pot procedure, can easily be purified by simple precipitation.

Acid-catalyzed condensation of levulinic acid and phenol into high yields of diphenolic acid (>50%) is possible with a combination of sulfonated hyperbranched polymers and thiol promotors, either added as a physical mixture or bound to the polymer by ion-pairing.

The heteracalixarene series (N/O/S) has been expanded with Se-bridged cyclotrimeric macrocycles. Selenacalix[3]triazines were synthesized by convenient one-pot nucleophilic aromatic substitution reactions and they showed peculiar supramolecular features. The N tridentate binding pocket was capable of coordinating both copper ions and anions.

We have prepared a UV-responsive polymeric superamphiphile, formed by a malachite green derivative and the double hydrophilic block copolymer methoxy-poly(ethylene glycol)(114)-block-poly(l-lysine hydrochloride)(200) (PEG-b-PLKC) on the basis of electrostatic interactions. The malachite green derivative undergoes photo-ionization upon UV irradiatio...

Innovative catalyst design holds the key to fundamental advances in the transformation of cellulose to chemicals and transportation fuels, both of which are vital to meet the challenge of increasing energy costs and the finite nature of fossil fuel reserves. Here we report on the functionalization, characterization and successful application of sul...

Homothiacalix[n]arenes have been largely underexposed compared with related (homo)heteracalixarenes, although their inherent structural features are particularly attractive for supramolecular host-guest chemistry. In this contribution, the synthetic macrocyclization protocols that afford homothiacalix[n]arenes have been reinvestigated and optimized...

Dendrons and dendrimers were convergently prepared using an isatin as AB2 monomer by superelectrophilic arylation in trifluoromethanesulfonic acid. This strategy has the advantage that incomplete reactions of the AB2 monomer are minimized, thus simplifying purification. As the obtained dendrons/dendrimers are analogues of the hyperbranched polymers...

Synthetic details and stationary and time-resolved photophysical properties of five BODIPY derivatives containing chalcogen atoms are presented. The photophysical data are compared to those of a chlorine atom containing BODIPY, acting as a reference. A strong impact in the HOMO–LUMO transition energy is achieved via nucleophilic substitution with c...

A novel family of homoselenacalix[n]arenes (n = 3-8), with bridging CH(2)SeCH(2) groups connecting the aryl subunits, has been synthesized via two different approaches employing nucleophilic Se species. The macrocycles are adequately characterized, including single-crystal X-ray structures for the homoselenacalix[4]- and homoselenacalix[6]arene hom...

Sulfide derivatives of diketopyrrolo[3,4-c]pyrrole (SDPPs) were prepared in a one-pot procedure from arylpyrrolinones, isothiocyanates and alkylating agents, and their properties as fluorophores were evaluated.

Nanomaterials are important due to their unique properties that may lead to new and exciting applications. Current scenario of application of nanotechnology in the field of corrosion prevention of metals is reviewed here. Recent research and developments in this area are discussed in designing efficient coating materials and alloys, which provide s...