Enantioselective Synthesis of 1,2-Benzothiazine 1-Imines via RuII /Chiral Carboxylic Acid-Catalyzed C-H Alkylation/Cyclization.

Sulfondiimines are diaza-analogues of sulfones with a chiral sulfur center. Compared to sulfones and sulfoximines, their synthesis and transformations have so far been studied to a lesser extent. Here, we report the enantioselective synthesis of 1,2-benzothiazine 1-imines, i.e., cyclic sulfondiimine derivatives from sulfondiimines and sulfoxonium ylides via C-H alkylation/cyclization reactions. The combination of [Ru(p-cymene)Cl2 ]2 and a newly developed chiral spiro carboxylic acid is key to achieving high enantioselectivity.

Zincation of Styrylsulfonium Salts.

We report the formation of zinc reagents by the reaction of styrylsulfonium salts with zinc powder. Transition metals and other additives are not required for promoting zincation. Zincation tolerates a variety of sensitive functional groups, including esters, bromides, and boronic esters, and proceeds with complete retention of stereochemistry. This method presents a practical approach to the formation of zinc reagents that can be used in a variety of functionalizations, such as halogenation, carboxylation, and Negishi cross-couplings.

Generation of Organozinc Reagents from Arylsulfonium Salts Using a Nickel Catalyst and Zinc Dust.

Readily available aryldimethylsulfonium triflates react with zinc powder under nickel catalysis via the selective cleavage of the sp2-hybridized carbon-sulfur bond to produce salt-free arylzinc triflates under mild conditions. This zincation displays superb chemoselectivity and thus represents a protocol that is complementary or orthogonal to existing methods. The generated arylzinc reagents show both high reactivity and chemoselectivity in palladium-catalyzed and copper-mediated cross-coupling reactions.

Iridium(III) Catalysts with an Amide-Pendant Cyclopentadienyl Ligand: Double Aromatic Homologation Reactions of Benzamides by Fourfold C-H Activation.

The synthesis, characterization, and catalytic performance of iridium(III) catalysts that bear an amide-pendant cyclopentadienyl ligand ([CpA IrI2 ]2 ) is reported. These [CpA IrI2 ]2 catalysts were obtained from the complexation of a CpA ligand precursor with [Ir(cod)OAc]2 followed by oxidation. Double aromatic homologation reactions of benzamides with alkynes by fourfold C-H activation proceeded in good to high yield with these [CpA IrI2 ]2 catalysts, demonstrating their superior catalytic performance in this challenging transformation.