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...