Desulfurative Functionalization of ß-Acyl Allylic Sulfides with N-H Free Indoles Highly Regioselective at C3 and N1 Positions: Rapid Access to α-Branched Enones.

A regiodivergent allylation of 1H-indoles highly selectively at the C3 and N1 positions with ß-acyl allylic sulfides through desulfurative C-C/C-N bond-forming reactions has been developed under mild conditions. Notably, the remarkable site-selective switch can be achieved by a delicate choice of solvents and bases. This cost-efficient method displays a broad substrate scope, good functional compatibility, and excellent site-selectivity, thus offering a divergent synthesis of indole substituted α-branched enones, which possess diverse potential opportunities for further applications and derivatization.

Palladium-Catalyzed Regioselective Coupling Cyclohexenone into Indoles: Atom-Economic Synthesis of ß-Indolyl Cyclohexenones and Derivatization Applications.

Herein, we report a palladium-catalyzed dehydrogenative cross-coupling of indoles with cyclic enones to give ß-indolyl cyclic enones under mild and neutral reaction conditions. The key to the success is to explore a mild condition, which ensures the indole C-H activation and subsequent syn ß-hydride elimination through rapid enolization isomerization of Pd(II)-enolate while suppressing other undesired side reactions. Synthetic utility has also been demonstrated in the flexible transformation of the coupling products to meta-phenols and benzo[a]carbazoles.

Palladium-Catalyzed Controllable Reductive/Oxidative Heck Coupling between Cyclic Enones and Thiophenes via C-H Activation.

Herein, we report a straightforward, environmentally friendly, and controllable palladium/ligand catalytic system to enable reductive/oxidative Heck reactions of cyclic enones with thiophene or furan derivatives via C-H activation. The key to this tunable reaction is the appropriate intercepting thienyl-Pd(II)-enolate during the enolization process. Such a controllable and economic protocol would not only provide efficient methods to construct various value-added ß-heteroarylated cyclic ketones/enones but also shed light on developing other conjugate addition reactions via C-H activation.

Palladium-catalyzed dehydrogenative coupling of cyclic enones with thiophenes: a rapid access to ß-heteroarylated cyclic enones.

Dehydrogenative coupling of cyclic enones with heteroarenes has been a longstanding challenge because of the competitive ketone dehydrogenation and conjugated addition. Herein, a dehydrogenative coupling reaction of cyclic enones of different sizes with substituted thiophenes to construct ß-thienyl cyclic enone compounds through palladium-catalyzed C-H functionalization under mild reaction conditions is reported. Simple substituted thiophenes with different functional groups can be directly introduced into cyclic enones with predominant regioselectivity at the α position of thiophene moieties and excellent functional group tolerance. Further molecular transformations of the coupling products to synthetically useful meta-heteroarylated phenol derivatives have also been demonstrated.

Acid Promoted Direct Cross-Coupling of Methyl Ketones with Dimethyl Sulfoxide: Access to Ketoallyl Methylsulfides and -sulfones.

A new strategy to prepare ß-acyl allylic methylsulfides and -sulfones through acid promoted direct cross-coupling of methyl ketones with dimethyl sulfoxide (DMSO) is reported. The reaction proceeded through the nucleophilic attack of enamine intermidiates derived from ketones to in situ generated thionium ion species, followed by elimination of methanthiol to give ketoallylic methylsulfides. With the prolonged reaction time, such products could be further reacted with a methyl sulfonyl radical, which might be generated from a methylthiosulfonate species, to afford ketoallylic methylsulfones in high yields. Molecular transformations of the allylic methylsulfides were also demonstrated.