A highly efficient addition-cyclization of N-methyl-N-arylacrylamides with arylaldehydes or benzenesulfonohydrazides was developed using a catalytic amount of the quaternary ammonium salt (TBAI) under metal-free conditions, leading to the carbonyl- and sulfone-containing oxindoles. Compared to previous methods, which require excessive amounts of explosive organic peroxides and precious or toxic metal reagents, the present protocol, which gave access to 3,3-disubstituted oxindoles, is a safe and green approach, resulting in the formation of various useful carbonyl- and sulfone-containing oxindoles in yields of 40-94%.

Thef irst facile one-pot synthesis of sulfone-containing oxindoles with easily accessible disulfides as the sulfonylating precursors is described. This reactiono ccurs smoothly under transition metal-free conditions ands hows excellent functional group tolerance,a llowing the facile ande fficient green synthesis of various sulfone-containing oxindoles in aqueous solution. Preliminary mechanistic studies reveal that both water (H 2 O) and potassium persulfate (K 2 S 2 O 8 )c an be the oxygens ource of the sulfone groups in the products. Scheme 3. Scope of disulfides. Reaction conditions: 1a (0.2 mmol), 2 (0.3 mmol), K 2 S 2 O 8 (3.0 equiv.), and CH 3 CN/H 2 O( 1:1, 2mL) at 80 8 8Cunder an N 2 atmosphere for 24 h; Isolated yields based on 1a.Scheme4.Gram-scale reaction.

An efficient iodocarbocyclization of alkenes for the synthesis of iodooxindoles has been developed. This reaction proceeds in a chemoselective manner and shows excellent tolerance of various functional groups, including a chemosensitive hydroxymethyl group. Nonmetal inorganic iodine pentoxide was used as both the oxidant and iodine source, making this protocol very practical. On the basis of experimental observations, a plausible electrophilic reaction mechanism was proposed.

Hydroxyl-containing compounds are highly value-added organic molecules, and the establishment of novel methodologies for their elaboration is a long-standing challenge in organic synthesis. Here the first oxone-mediated direct arylhydroxylation of...

The first visible light-induced dioxygenation of α,β-unsaturated amides with N-hydroxy compounds under air atmosphere was developed with the use of non-toxic organic dye rose bengal as the photoredox catalyst. This...

Carbonyl-containing oxindoles can be prepared from N-arylacrylamides and α-diketones by TBHP- or oxone (KHSO5)-mediated C(sp(2))-C(sp(2)) bond cleavage and new C(sp(2))-C(sp(3)) bond formation. This methodology is characterized by its simple and transition-metal-free conditions and good functional group compatibility utilizing inexpensive and readily available reagents, thus providing a practical and efficient approach to an important class of 3-(2-oxoethyl)indolin-2-ones which are highly valued synthetic intermediates of biologically active molecules. In this transformation, alkylcarbonyl-containing oxindoles were obtained in majority when N-arylacrylamides reacted with asymmetric aliphatic/aromatic α-diketones. On the basis of the preliminary experiments, a plausible mechanism of this transformation is disclosed.

An efficient oxidative aminooxyarylation of alkenes under a transition-metal-free condition was described. Under the reaction conditions, N-hydroxyphthalimide (NHPI) reacted readily with N-arylacrylamides to produce cyclic products via a radical C-H functionalization process, achieving both C-O and C-C bonds formation in one pot. This reaction provided a facile access to the valuable aminooxylated oxindoles. The benzylic and α-methylene C(sp)-H bonds were also aminooxylated under the reaction conditions.

A metal-free synthesis of oxindoles was achieved through the (NH4)2S2O8-mediated halocarbocyclization of alkenes. This protocol provides a practical and environmentally benign method for the construction of halo-containing oxindoles in water. The advantages of this reaction are its good functional group tolerance and mild reaction conditions. On the basis of experimental observations, a plausible reaction mechanism is proposed.