Anhydrous ferric chloride adsorbed on silica gel induced ring enlargement of tertiary cyclobutanols

Bis-indolylation of aldehydes and ketones using silica-supported FeCl3: molecular docking studies of bisindoles by targeting SARS-CoV-2 main protease binding sites

We report herein an operationally simple, efficient and versatile procedure for the synthesis of bis-indolylmethanes via the reaction of indoles with aldehydes or ketones in the presence of silica-supported ferric chloride under grindstone conditions. The prepared supported catalyst was characterized by SEM and EDX spectroscopy. The present protocol has several advantages such as shorter reaction time, high yield, avoidance of using harmful organic solvents during the reaction and tolerance of a wide range of functional groups. Molecular docking studies targeted toward the binding site of SARS-CoV-2 main protease (3CL^pro or M^pro) enzymes were investigated with the synthesized bis-indoles. Our study revealed that some of the synthesized compounds have potentiality to inhibit the SARS-CoV-2 M^pro enzyme by interacting with key amino acid residues of the active sites via hydrophobic as well as hydrogen bonding interactions.

Silica supported FeCl₃ catalyzed simple protocol for the synthesis of bis-indolylmethanes was explored via grindstone chemistry. Synthesized compounds were screened virtually as inhibitor by targeting the binding site of SARS-CoV-2 main protease enzyme.

Construction of 2,2-Dimethyloxepane Frameworks from Ene-Diols Catalyzed by Metal Catalyst or Brønsted Acid via 7-Endo-Trig Cyclization

The synthesis of 2,2-dimethyloxepane frameworks based on the 7-endo-trig cyclization of ene-diol using a catalytic amount of metal catalysts (Au, Ag) or Brønsted acid (TfOH) has been developed. Also, the spiro-type dioxabicyclic products were also derived from the diene-diols. For the condition using metal catalysts, the cyclization selectively reacted between the 1,1,3-trisubstituted alkenes and alcohols to form the 2,2-dimethyloxepane frameworks. On the other hand, the TfOH reacted with not only the 1,1,2-trisubstituted alkene, but also the 1-substituted and 1,2-disubstituted alkenes providing the corresponding cyclic ethers, which is quite different from the conditions of the metal catalysts.

Environmentally benign syntheses of hexahydro-cyclopenta(b)furan and 2-oxabicyclo[3.2.1]octane derivatives

Amberlyst-15® catalyzes efficient synthesis of hexahydro-cyclopenta(b)furan and 2-oxabicyclo[3.2.1]octane derivatives from campholenic alcohols.

Synthesis of pyrrolinylnaphthalenes and evaluation of their antinociceptive activity

In this paper the regioselective preparation of (R/S)-1,2-dimethyl-3-[2-(6-substituted naphthyl)]-2H,5H-pyrrolines 2a-d is reported. These compounds were prepared by thermal dehydration of the corresponding alcohols (2R,3S/2S,3R)-1,2-dimethyl-3-[2-(6-substituted naphthyl)]-3-hydroxy-pyrrolidines (2R,3S/2S,3R)-1a-d with anhydrous FeCl3-SiO2, under vacuum. Pharmacological properties of (R/S)-2a-d are also described. Analgesic activity was investigated by the hot plate test, also in the presence of selective antagonists of mu, delta and kappa opioid receptors. Preliminary analysis of the side-effects was also accomplished using the rota-rod test. Interesting antinociceptive activity was shown by all compounds and in particular by (R/S)-2a (AD50 = 0.31 mg/kg); delta opioid receptors were found to be mainly involved in the pharmacological process and, in general, it was found that the compounds influenced locomotory activity to a much lesser extent than did morphine.