Dimethyl Sulfoxide Provides Three Different Units in Synthesis of Chroman-4-ones Containing Sulfur and a Quaternary Carbon Center under HOAc Conditions.

HOAc-promoted construction of chroman-4-ones with a sulfur atom and an α-carbonyl quaternary carbon center directly from ortho-hydroxyacetophenones and DMSO is described. In these unique reactions, DMSO is activated by HOAc and provides three different units (CH2, CH2OH, and CH2SMe) in the target molecules. This reaction displays good substrate scope and reaction yields with a series of substitutes. The mechanism showed that the three units were formed in sequential order.

Modular synthesis of (E)-cinnamaldehydes directly from allylarenes via a metal-free DDQ-mediated oxidative process.

An efficient synthesis of (E)-cinnamaldehydes by a metal-free DDQ-mediated oxidative transformation of allylarenes was developed. The protocol provides a practical method to prepare diverse (E)-cinnamaldehydes with broad functional group tolerance in good to excellent yields, including easy access to natural products randainal and geranyloxy sinapyl aldehyde from plant extracts. Finally, the mechanism of a single-electron transfer process was proposed.

Synthesis of 3-acylindoles by palladium-catalyzed acylation of free (N-H) indoles with nitriles.

An efficient palladium-catalyzed synthesis of 3-acylindoles using free (N-H) indoles and nitriles has been developed. The acylation reaction proceeded well under the Pd(OAc)(2)/2,2'-bipyridine system and with D-(+)-camphorsulfonic acid as the additive. A possible mechanism involving carbopalladation of nitriles and subsequent hydrolysis of ketimines is proposed.

Palladium-catalyzed ortho-alkoxylation of anilides via C-H activation.

A palladium-catalyzed ortho-alkoxylation of anilides with both primary and secondary alcohols via ligand-directed C-H activation has been explored. This alkoxylation promoted by catalytic methanesulfonic acid proceeds well at room temperature in most cases and affords aryl alkyl ethers in moderate to good yields.

Palladium-catalyzed oxidative tandem reaction of allylamines with aryl halides leading to alpha,beta-unsaturated aldehydes.

A novel tandem protocol involving a Heck reaction process for the synthesis of alpha,beta-unsaturated aldehydes has been developed. In the presence of Pd(OAc), PPh3, NaOAc, TBAB and air, N-allylbenzenamines underwent the reaction with various aryl halides to afford the corresponding alpha,beta-unsaturated aldehydes selectively in moderate to good yields. The protocol can also be used as a valuable route for the deallylation of arylamines.

Palladium-catalyzed intramolecular 5-exo-dig hydroarylations of N-arylpropiolamides: thermodynamics-controlled stereoselective synthesis of 3-methyleneoxindoles.

Palladium-catalyzed intramolecular hydroarylation of N-arylpropiolamides has been developed for the stereoselective synthesis of 3-(monosubstituted methylene)oxindoles. In the presence of Pd(OAc)(2) and dppf, a variety of N-arylpropiolamides successfully underwent the intramolecular hydroarylation reaction to afford the corresponding 3-(monosubstituted-methylene)oxindoles in moderate to excellent yields. It is noteworthy that the stereoselectivity of the reaction can be controlled by varying the reaction temperature.