Base-Mediated C4-Selective C−H-Sulfonylation of Pyridine**

The direct regioselective C−H-functionalization of simple, unfunctionalized pyridines is considered a long-standing challenge in heterocyclic chemistry. Herein, we report a novel one-pot protocol for the C4-selective sulfonylation of pyridines via triflic anhydride (Tf2O) activation, base-mediated addition of a sulfinic acid salt, and subsequent elimination/re-aromatization. Contrary to previous approaches employing tailored blocking groups, positional selectivity can be controlled by using N-methylpiperidine as simple, readily available external base. This method offers a highly modular and streamlined access to C4-sulfonylated pyridines

Base-mediated C4-selective C-H-sulfonylation of pyridine

The direct regioselective C-H-functionalization of simple, unfunctionalized pyridines is considered a long-standing challenge in heterocyclic chemistry. Herein, we report a novel one-pot protocol for the C4-selective sulfonylation of pyridines via triflic anhydride (Tf2O) activation, base-mediated addition of a sulfinic acid salt and subsequent elimination/rearomatization. Contrary to previous approaches employing tailored blocking groups, positional selectivity can be controlled by using N-methyl piperidine as simple, readily available external base. This method offers a highly modular and streamlined access to C4-sulfonylated pyridine

A Enamide-Based Diastereoselective Synthesis of Isoindolo[2,1-a]quinolin-11(5H)-ones with Three Contiguous Stereogenic Centers

A stereoselective synthesis of isoindolo[2,1-a]quinolin-11(5H)-ones containing three contiguous stereogenic centers is described. This Lewis-acid mediated reaction of enamides with N-aryl-acylimines affords the desired fused heterocyclic isoindolinones in high yields and diastereoselectivities. Scope and limitations of this method are discussed. The stereochemical outcome of this transformation indicates a stepwise reaction pathway

A Enamide-based diastereoselective synthesis of isoindolo[2,1-a]quinolin-11(5H)-ones with three contiguous stereogenic centers

A stereoselective synthesis of isoindolo[2,1-a]quinolin-11(5H)-ones containing three contiguous stereogenic centers is described. This Lewis-acid mediated reaction of enamides with N-aryl- affords the desired fused heterocyclic isoindolinones in high yields and diastereoselectivities. Scope and limitations of this method are discussed. The stereochemical outcome of this transformation indicates a stepwise reaction pathway

Palladium-Catalyzed Enantioselective Three-Component Synthesis of α‑Substituted Amines

The first general palladium-catalyzed, enantioselective three-component synthesis of α-arylamines starting from sulfonamides, aldehydes, and arylboronic acids has been developed. These reactions generate a wide array of α-arylamines with high yields and enantioselectivities. Notably, this process is tolerant to air and moisture, providing an operationally simple approach for the synthesis of chiral α-arylamines

Arylation of Lithium Sulfinates with Diaryliodonium Salts: A Direct and Versatile Access to Arylsulfones

An efficient, transition-metal-free arylation of lithium sulfinates, which are readily accessible from reactions of organolithium reagents with sulfur dioxide, is described. Based on this method, a practical protocol for the direct transformation of (hetero)arenes and (hetero)aromatic halides into diarylsulfones was developed

Recent Advances in the Synthesis and Direct Application of Sulfinate Salts

Sulfinate salts have attracted considerable attentions due to their versatile reactivity. They have emerged as highly useful building blocks for the construction of all kinds of sulfonyl-group containing molecules, such as sulfones or sulfonamides, and for the construction of various carbon–carbon- and carbon–heteroatom-bonds via sulfur dioxide (SO2) extrusion. Herein, we want to summarize the latest developments in the synthesis of sulfinate salts. Both improvement of classical methods and the development of various novel protocols will be discussed. Also selected one-pot methods directly utilizing in situ generated sulfinate salts as intermediates will be covered in this review article

Metal-Free Synthesis of Diaryl Sulfones from Arylsulfinic Acid Salts and Diaryliodonium Salts

An efficient, high-yielding, and transition-metal-free synthesis of diaryl sulfones from arylsulfinic acid salts and diaryliodonium salts has been developed. The mild reaction conditions tolerate a range of functional groups, and unsymmetrical diaryliodonium salts show high chemoselectivity

One-Pot Synthesis of Aryl Sulfones from Organometallic Reagents and Iodonium Salts

A transition-metal-free arylation of lithium, magnesium, and zinc sulfinates with diaryliodonium salts is described. The sulfinic acid salts were prepared from the reaction of the corresponding organometallic reagents and sulfur dioxide. Combination of the three single steps (preparation of the organometallic compound, sulfinate formation, and arylation) leads to a one-pot sequence for the synthesis of aryl sulfones from simple starting materials. The chemoselectivity of unsymmetrical diaryliodonium salts has been investigated. Potential and limitations of this method will be discussed