Facile Chemoselective synthesis of 2-(2-(Methoxycarbonyl)-3-oxo-2,3-dihydrobenzofuran-2-yl)benzoic acids and 3H,3’H-Spiro[benzofuran-2,1′-isobenzofuran]-3,3′-dione derivatives

Dihydro-10H-indeno[1,2-b]benzofurans and Tetrahydroindeno[1,2-c]isochromenes via Stereoselective Intramolecular Carbocation Cascade Cyclization

Nazarov cyclization of the (E)-(2-stilbenyl)methanols under the catalysis of p-TsOH immobilized on silica (PTS-Si) proceeded to give the corresponding indanyl cation with the exclusive trans relationship at the two newly formed adjacent stereogenic centers. The ensuing intramolecular nucleophilic addition by the MOM-protected phenol (m = 0) or benzyl alcohol (m = 1) furnished the Indane-fused benzofuran [5/5] or isochroman [5/6] system, respectively, with the exclusive cis stereocontrol at the two-carbon ring junction. Thus, in a single step, from nonchiral starting materials, the intramolecular cascade carbocation cyclization (CCC) furnished the [5/5] or [5/6] oxygen-containing Indane fused-ring systems in moderate to good yields with excellent stereoselectivity on all three contiguous stereogenic centers.

DABCO-based ionic liquid-promoted synthesis of indeno-benzofurans derivatives: Investigation of antioxidant and antidiabetic activities

A simple and effective method for synthesis of indeno-benzofurans derivatives using polyphenols and ninhydrins is explored using an acidic catalyst based on DABCO (1,4-diaza bicycle [2.2.2] octane)-based ionic liquid. The products of these types of reactions have very low yields without catalysts, but with DABCO-AIL, the yields are excellent, reaction times are reduced, and the media are cleaner. Using infrared (IR), proton nuclear magnetic resonance (1H NMR), Carbon-13 nuclear magnetic resonance (13C NMR), and mass spectrometry, the structures of products can be confirmed. There is evidence that oxidative stress plays a role in the pathophysiology of numerous diseases, including diabetes. Therapeutic antioxidants are promising candidates for the prevention and treatment of such diseases. To investigate the antioxidant properties of all synthesized derivatives, the 2,2-diphenyl-1-picrylhydrazylhydrazyl-hydrate (DPPH) assay was used. Derivatives 3d and 4 with the highest antioxidant effect (with IC50 value of 0.015 µmol/mL) were selected to evaluate the anti-diabetic effect using the Bernfeld method. The best result was seen at 0.8 mg/mL of 4 derivative and results of the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) test revealed that 4 at this concentration lacked cellular toxicity, too.

One-pot synthesis of new alkyl 1-naphthoates bearing quinoline, pyranone and cyclohexenone moieties via metal-free sequential addition/oxidation reactions

A mild and one-pot synthetic pathway was successfully developed for the synthesis of new naphthoate-based scaffolds containing quinoline, pyranone and cyclohexenone moieties via a multistep reaction between acenaphthoquinone and various 1,3-diketones in the presence of different primary aliphatic and benzylic alcohols. This reaction proceeds via a sequential addition/oxidation mechanistic process including a metal-free addition step of acenaphthoquinone and 1,3-diketones followed by the H₅IO₆-mediated C–C oxidative cleavage of the corresponding vicinal diols at room temperature. The alcohols play a dual role, as the reaction solvent as well as the nucleophile, to conduct the reaction process toward naphthoate formation. All alkyl naphthoate derivatives prepared in this work are new compounds and were definitively characterized using ¹H-NMR, ¹³C-NMR and HRMS analysis, while X-ray crystallography was carried out for one of the products. The synthesis of a naphthalene-based nucleus attached to heterocyclic moieties is noteworthy to follow in the near future for diverse applications in biology, medicine, metal complex design, and semiconductor and optical materials.

Various new alkyl 1-naphthoates bearing quinoline, pyranone and cyclohexenone moieties were successfully synthesized by a one-pot sequential addition/oxidation process.

One-Pot Synthesis of Spiro-isobenzofuran Compounds via the Sequential Condensation/Oxidation Reaction of Ninhydrin with 4-Amino-1,2-naphthoquinones/2-Amino-1,4-naphthoquinones under Mild Conditions

A one-pot route for the synthesis of spiro-isobenzofuran compounds was developed via the condensation reaction of ninhydrin with 4-amino-1,2-naphthoquinones or 2-amino-1,4-naphthoquinones in acetic acid followed by the oxidative cleavage of the corresponding vicinal diols at room temperature. Various derivatives of spiro[benzo[g]indole-2,1'-isobenzofuran]-3,3',4,5(1H) tetraones and spiro[benzo[f]pyrrolo[2,3-h]quinoxaline-2,1'-isobenzofuran]-3,3'(1H)-diones were synthesized in good to high yields. Moreover, further condensation of spiro[benzo[g]indole-2,1'-isobenzofuran]-3,3',4,5(1H)-tetraones with 1,2-diamines resulted in the new spiro-isobenzofuran compounds having phenazine rings in high yields.