An efficient synthesis of dihydrofuranyl spirooxindoles from isatin-derived propargylic alcohols and 1,3-dicarbonyls

Enantioselective synthesis of 3-hydroxy- and 3-amino-3-alkynyl-2-oxindoles by the dimethylzinc-mediated addition of terminal alkynes to isatins and isatin-derived ketimines

A common protocol for enantioselective alkynylation of isatins and isatin-derived ketimines using terminal alkynes and Me2Zn in the presence of a catalytic amount of a chiral perhydro-1,3-benzoxazine with moderate to excellent enantioselectivity under mild reaction conditions is described. The additions to ketimines present a novel approach to chiral amines being derivatives of oxindoles. The reaction is broad in scope with respect to aryl- and alkyl-substituted terminal alkynes and isatin derivatives. In isatins, the alkynylation occurs at the Si face of the carbonyl group, whereas in the ketimine derivatives it occurs at the Re face of the imine.

Novel cellulose supported 1,2-bis(4-aminophenylthio)ethane Ni(ii) complex (NiII(BAPTE)(NO3)2-Cell) as an efficient nanocatalyst for the synthesis of spirooxindole derivatives

Cellulose was used as a support for immobilizing a Ni(ii) complex of 1,2-bis(4-aminophenylthio)ethane to prepare Ni^II(BAPTE)(NO₃)₂-Cell as a new organo–inorganic hybrid nanocatalyst. The properties of the prepared catalyst were studied using various analyses such as FT-IR, XRD, SEM, TGA and EDX. Ni^II(BAPTE)(NO₃)₂-Cell was employed as a reusable catalyst for the synthesis of spirooxindole derivatives via a three-component condensation of isatin, malononitrile and reactive methylene compounds. The nanocatalyst can be readily and quickly separated from the reaction mixture and can be reused for at least eight successive reaction cycles without a significant reduction in efficiency. The facile accessibility to the starting materials, use of green solvents and conducting the reactions in eco-friendly and cost-effective conditions have made this protocol a suitable method for preparing spirooxindole derivatives.

Ni^II(BAPTE)(NO₃)₂-Cell as a novel cellulose supported catalyst has been prepared and characterized by various techniques including FT-IR, XRD, SEM, TGA and EDX.

Stereoselective sulfenylation of oxindole-derived propargyl alcohols to access sulfenylated-3-alkenyloxindoles

A Ca-catalyzed, tetrasubstituted alkenyl-sulfenylation was achieved using readily available aryl/alkyl thiols and easily prepared oxindole-derived propargyl alcohols under solvent-free conditions. The reaction proceeded with hydrogen bonding assisted regioselective α-thiolation and subsequent calcium catalyzed stereoselective alkenylation to yield E-alkenyl thioethers with high diastereoselectivity.

Protecting group-directed annulations of tetra-substituted oxindole olefins and sulfur ylides: regio- and chemoselective synthesis of cyclopropane- and dihydrofuran-fused spirooxindoles

Protecting group-controlled regio- and chemoselective synthesis of cyclopropane- and dihydrofuran-fused spirooxindoles containing vicinal quaternary carbon centers.

Synthesis of 2-substituted 3-chlorobenzofurans via TMSCl-mediated nucleophilic annulation of isatin-derived propargylic alcohols

A TMSCl-mediated cascade annulation of isatin-derived propargylic alcohols for the synthesis of 2-substituted 3-chlorobenzofurans is now reported. Mechanistic investigations showed that this proceeded through a sequential Meyer-Schuster rearrangement/nucleophilic addition/intramolecular annulation. TMSCl not only acts as a promoter, but also acts as a chlorine source in this protocol.

An efficient, room temperature, oxygen radical anion (O2•−) mediated, one-pot, and multicomponent synthesis of spirooxindoles

The present report highlights an efficient use of oxygen radical anion to promote a room temperature multi-component synthesis of spirooxindoles (4a–4l) under mild reaction conditions. The potassium superoxide (KO2) and tetraethylammonium bromide (TEAB) combination generate the oxygen radical anion in situ to promote this transformation. This method offers a sustainable and direct access to the biologically important spirooxindole derivatives in good to excellent yields.

Synthesis of Isoxazolopyridines and Spirooxindoles under Ultrasonic Irradiation and Evaluation of Their Antioxidant Activity

New polycyclic-fused isoxazolo[4,5-e]pyridines and spirooxindoles were obtained via multicomponent reaction of 5-amino-3-methylisoxazole, indan-1,3-dione, and aromatic aldehydes and reaction of 5-amino-3-methylisoxazole, isatin, and β-diketones in the presence of (±)-camphor-10-sulfonic acid as an effective and nontoxic organocatalyst under ultrasound-promoted conditions. The antioxidant activity of the novel synthesized compounds was studied.