Samuel Thurow

Synthesis of bis(indolyl)methanes using ammonium niobium oxalate (ANO) as an efficient and recyclable catalyst

A green and efficient procedure was developed for the synthesis of bis(indolyl)methanes using ammonium niobium oxalate (ANO) NH4[NbO(C2O4)2(H2O)x]·nH2O as the catalyst and water or glycerol as the solvent. Products were obtained in good to excellent yields under conventional heating (water, 50 °C) or under sonication (glycerol, 110 °C). In the reaction in water, the catalyst was easily reused for further reactions without loss of activity.

Sonochemistry: An efficient alternative to the synthesis of 3-selanylindoles using CuI as catalyst

Ultrasonic (US) irradiation was successfully used as an alternative energy source to prepare 3-selanylindoles through the direct selanylation of indoles with diorganyl diselenides using CuI (20 mol%) as catalyst and DMSO as the solvent. By using this US-promoted reaction, eleven 3-organylselanylindoles were prepared selectively and in good yields. A comparative study between the reactions under conventional heating, microwave and ultrasound irradiations was performed, and it was observed advantage in using US over the other heating systems.

Metal and base-free synthesis of arylselanyl anilines using glycerol as a solvent

We describe here a metal and base-free straightforward method to access arylselanyl anilines using glycerol as a solvent. Starting from N,N-disubstituted anilines and arylselanyl chloride, the protocol is general and was successfully applied to a sort of anilines with different substitution patterns in both the aromatic ring and the nitrogen atom. As desirable for a green synthetic procedure, the non-toxic, low volatile, renewable glycerol was used as a solvent at room temperature.

A Selenium-Based Ionic Liquid as a Recyclable Solvent for the Catalyst-Free Synthesis of 3-Selenylindoles

The ionic liquid 1-butyl-3-methylimidazolium methylselenite, [bmim][SeO2(OCH3)], was successfully used as solvent in the catalyst-free preparation of 3-arylselenylindoles by the reaction of indole with ArSeCl at room temperature. The products were obtained selectively in good yields without the need of any additive and the solvent was easily reused for several cycles with good results.

Ultrasound-promoted copper-catalyzed synthesis of bis-arylselanyl chrysin derivatives with boosted antioxidant and anticancer activities

Herein we report the use of ultrasonic irradiation (US) in the synthesis of six new semi-synthetic selenium-containing chrysin derivatives by a simple and effective methodology utilizing CuI as catalyst, in good to excellent yields (60-89%). It was observed that US accelerates the reaction compared to conventional heating with excellent selectivity for diselenylated products. Compounds were tested for their antioxidant and anticancer activities in vitro and it was observed that the presence of selenium in the A-ring of chrysin enhanced both antioxidant and anticancer properties. Semi-synthetic 6,8-bis(o-tolylselanyl)-chrysin 3b has the best radical scavenging activity of DPPH (Imax: 39.79µM) and ABTS+ (IC50: 6.5µM) radicals. Similarly, in the Reactive Species (RS) assay, 3b showed high antioxidant activity in mice cortex (IC50: 5.67µM), whereas 6,8-bis(p-anisoylselanyl)-chrysin 3c was the more active in the hippocampus (IC50: 5.63µM). The Se-chrysins were effective in prevention of lipid peroxidation, highlighting 6,8-bis(p-fluorophenylselanyl)-chrysin 3d in cortex (IC50: 0.54µM) and 3b in hippocampus (IC50: 0.27µM). In addition, 3d was effective in inhibiting human lung adenocarcinoma (A549) cells growth, with a IC50 of 19.9µM after 72h of treatment, while 6,8-bis(p-anisoylselanyl)-chrysin 3c presented the higher antiproliferative activity after 48h of treatment (IC50 of 41.4µM).

Reduction of Selenoamides to Amines Using SmI2–H2O

Selenoamides are selectively reduced to amines by SmI2 with H2O. The process is general for primary, secondary, and tertiary aryl and alkyl selenoamide substrates and selectively delivers amine products. The reduction proceeds under mild conditions using SmI2 activated by straightforward addition of H2O, and does not require an additional Lewis base additive.

Selenium dioxide-promoted selective synthesis of mono- and bis-sulfenylindoles

A selective method for the preparation of mono- and bis-sulfenylindoles was developed using an oxidizing agent and the I2/SeO2 system as an efficient catalyst. The selectivity was controlled by varying the amount of SeO2. This represents the first example of the application of SeO2 in this type of selective chemistry.

Structural diversity in the products formed by the reactions of 2-arylselanyl pyridine derivatives and dihalogens

The reactivity of the 2-arylselanyl pyridine derivatives L1–L4 towards dihalogens X2 (X = I, Br) and interhalogens IX (X = Cl, Br) was studied in CHCl3 or CH3CN. The solid products obtained were structurally characterized and their nature points out the preference for CT spoke adducts and for seesaw insertion adducts to be formed at the N-donor and Se-donor site, respectively. DFT calculations were performed to provide a rationale for the structural diversity observed in the products obtained.

An improved solvent-free procedure for synthesis of bis(indolyl)methanes

Because of BIM’s versatile biological activities, in particular the pharmacological one, various methods are mentioned for their preparation. 3 A drawback of most of the described methods is the use of expensive and toxic reagents and volatile solvents. In this work, because of our interest in the development of new efficient and green methodologies, we decided to study the electrophilic substitution reaction of indoles with carbonyl compounds to obtain bis(indolyl)methanes using silica gel as recyclabe catalyst.