Ludovic Paquin

Acidic task-specific ionic liquid as catalyst of microwave-assisted solvent-free Biginelli reaction

A simple and effective synthesis of 3,4-dihydropyrimidin-2(1H)-one and 3,4-dihydropyrimidine-2(1H)-thione derivatives has been developed on the basis of three-component condensation of substituted aromatic and heterocyclic aldehydes, methyl acetoacetate, and urea or thiourea in the presence of 10% of an acidic task-specific ionic liquid ([C4mim][HSO4]) as catalyst under microwave irradiation in the absence of a solvent. The proposed procedure ensures short reaction times (4.4–8 min) and good yields after purification by recrystallization.

Synthesis and preliminary biological evaluation of new derivatives of the marine alkaloid leucettamine B as kinase inhibitors.

New derivatives of the marine alkaloid leucettamine B were prepared in five steps with overall yields ranging from 23 to 30%. The key step of our strategy has been the sulfur/nitrogen displacement under solvent-free microwave irradiation of (5Z) 5-benzo[1,3]-dioxo-5-ylmethylene-2-ethylsulfanyl-3,5-dihydroimidazol-4-one 3 with a mono-protected ethylenediamine 2. After deprotection of the N-Boc group, the amino derivative of leucettamine B 5 was subjected to reductive amination in two steps with retention of configuration of the double bond, to lead to eight new analogs of leucettamine B. The effect of these compounds on CK1alpha/beta, CDK5/p25, and GSK-3alpha/beta were investigated.

One-Pot Synthesis of 5-Arylidene-2-Imino-4-Thiazolidinones under Microwave Irradiation

A rapid and easy solvent free one-pot synthesis of 5-arylidene-2-imino-4-thiazolidinones by condensation of the thioureas with chloroacetic acid and an aldehyde under microwave-irradiation is described.

Synthesis and toxicity evaluation of hydrophobic ionic liquids for volatile organic compounds biodegradation in a two-phase partitioning bioreactor

Synthesis of several hydrophobic ionic liquids (ILs), which might be selected as good candidates for degradation of hydrophobic volatile organic compounds in a two-phase partitioning bioreactor (TPPB), were carried out. Several bioassays were also realized, such as toxicity evaluation on activated sludge and zebrafish, cytotoxicity, fluoride release in aqueous phase and biodegradability in order to verify their possible effects in case of discharge in the aquatic environment and/or human contact during industrial manipulation. The synthesized compounds consist of alkylimidazoliums, functionalized imidazoliums, isoqinoliniums, triazoliums, sulfoniums, pyrrolidiniums and morpholiniums and various counter-ions such as: PF6(-), NTf2(-) and NfO(-). Toxicity evaluation on activated sludge of each compound (5% v/v of IL) was assessed by using a glucose uptake inhibition test. Toxicity against zebrafish and cytotoxicity were evaluated by the ImPACCell platform of Rennes (France). Fluoride release in water was estimated by regular measurements using ion chromatography equipment. IL biodegradability was determined by measuring BOD28 of aqueous samples (compound concentration,1mM). All ILs tested were not biodegradable; while some of them were toxic toward activated sludge. Isoquinolinium ILs were toxic to human cancerous cell lines. Nevertheless no toxicity was found against zebrafish Danio rerio. Only one IL released fluoride after long-time agitation.

Prospective study directed to the synthesis of unsymmetrical linked bis-5-arylidene rhodanine derivatives via “one-pot two steps” reactions under microwave irradiation with their antitumor activity

We here report on the synthesis of new unsymmetrical linked bis-5-arylidene rhodanine derivatives with stereocontrolled Z-configuration. The 6 steps synthesis was achieved and the key steps are the construction of the two 5-arylidene rhodanine moieties using an “one-pot two-steps” method under microwave dielectric heating in a closed reactor. The intermediates 6, 7 and desired unsymmetrical compounds 9 have been also evaluated for their in vitro inhibition of cell proliferation (Huh7 D12, Caco2, MDA-MB 231, HCT116, and NCI-H727 tumoral cell lines). Two of all compounds have shown potent activity against Huh7 D12, Caco2, and MDA-MB 231.Graphical Abstract.

Synthesis of New N,N'-Bis(5-arylidene-4-oxo-4,5-dihydrothiazolin-2-yl)piperazine Derivatives Under Microwave Irradiation and Preliminary Biological Evaluation.

New N,N’-bis(5-arylidene-4-oxo-4,5-dihydrothiazoline-2-yl)diamine derivatives 5 were prepared in two steps from rhodanine and piperazine, or 1,4-bis(3-amino-propyl)piperazine, under microwave reaction conditions with retention of configuration. Some of these compounds were tested for in vitro antiproliferative activities and for their kinase inhibitory potencies towards six kinases (CDK5/p25, GSK3α/β, DYRK1A, DYRK2, CLK1, and CLK2). The compound 5d showed nanomolar activity towards DYRK1A kinase (IC50 = 0.041 μM).

A Practical Approach to New (5Z) 2-Alkylthio-5-arylmethylene-1-methyl-1,5-dihydro-4H-imidazol-4-one Derivatives

A practical protocol for the preparation of (5Z)-2-alkylthio-5-arylmethylene-1-methyl-1,5-dihydro-4H-imidazol-4-one derivatives is reported. The new compounds were obtained in good yield and stereoselectivity in two steps, namely a solvent-free Knoevenagel condensation under microwave irradiation, followed by an S-alkylation reaction with various halogenoalkanes.

Sample preparation for an optimized extraction of localized metabolites in lichens: Application to Pseudevernia furfuracea

Lichens are symbiotic organisms known for producing unique secondary metabolites with attractive cosmetic and pharmacological properties. In this paper, we investigated three standard methods of preparation of Pseudevernia furfuracea (blender grinding, ball milling, pestle and mortar). The materials obtained were characterized by electronic microscopy, nitrogen adsorption and compared from the point of view of extraction. Their microscopic structure is related to extraction efficiency. In addition, it is shown using thalline reactions and mass spectrometry mapping (TOF-SIMS) that these metabolites are not evenly distributed throughout the organism. Particularly, atranorin (a secondary metabolite of interest) is mainly present in the cortex of P. furfuracea. Finally, using microwave assisted extraction (MAE) we obtained evidence that an appropriate preparation can increase the extraction efficiency of atranorin by a factor of five.

Absorption of Hydrophobic Volatile Organic Compounds in Ionic Liquids and Their Biodegradation in Multiphase Systems

The coupling of absorption in a gas-liquid contactor and biodegradation in a two-phase partitioning bioreactor (TPPB) has been shown to be a promising technology for the removal of hydrophobic volatile organic compounds. The choice of the organic phase is crucial, and consequently only two families of compounds comply with the requested criteria, silicone oils and ionic liquids. These latter solvents appear especially promising owing to their absorption capacity towards hydrophobic compounds and their low volatility, as well as the possibility of IL tailoring, allowing a fine-tuning of their physicochemical properties, leading to a wide range of products with various characteristics. Some results on common ionic liquids are highlighted in this chapter: biodegradation rates reported by some authors show that phenol biodegradation in the presence of ILs is up to 40 % higher than those obtained in other multiphase reactors; there is a strong affinity of toluene and DMDS for imidazolium salts, [C4Mim][PF6] or [C4Mim][NTf2]. Performance improvements may be expected from the tailoring of ionic liquid structure, especially towards toxicity reduction. Positive results recorded after cell acclimation to target compounds let expect an important gain from more complex acclimation strategies, including microbial acclimation to both ionic liquids and pollutants.

Ionic liquid-phase organic synthesis (IoLiPOS) methodology applied to cross aldol reaction

Cross aldol reaction in task-specific ionic liquids was developed. Ionic liquid-phase bound aldehyde reacted with various ketones (acetone, cyclopentanone, and butan-2-one) with l-proline as catalyst to afford various ionic liquid-phase supported aldols in yields ranging from 81 to 99%. Detachment of the aldol in MeOH was realized by transesterification using 15% of MeONa. The structure of intermediates in each step was verified by spectroscopic analysis.