A direct α-Csp-H methylenation of arylketones to form C═C bond using dimethyl sulfoxide as one-carbon source is achieved under transition metal-free reaction condition. Various aryl ketone derivatives react readily with DMSO, producing the α,β-unsaturated carbonyl compounds in yields of 42 to 90%. This method features a transition metal-free reaction condition, wide substrate scope and using DMSO as novel one-carbon source to form C═C bond, thus providing an efficient and expeditious approach to an important class of α,β-unsaturated carbonyl compounds. Based on the preliminary experiments, a plausible mechanism of this transformation is disclosed.

A coupling of multiple C(sp)-H bonds of the methyl group in methyl ketones with dimethyl sulfoxide is developed. This coupling allows the direct C(sp)-H bond coupling among three methyl groups and affords one C-C bond and one C[double bond, length as m-dash]C bond under transition metal-free conditions. The value-added cyclized 3-methylthiomethyl chroman-4-ones can be synthesized through this method. A plausible mechanism is proposed.

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.

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.