Recent Progress and Emerging Technologies towards a Sustainable Synthesis of Sulfones

Sulfones play a pivotal role in modern organic chemistry. They are highly versatile building blocks and find various applications as drugs, agrochemicals, or functional materials. Therefore, sustainable access to this class of molecules is of great interest. Herein, the goal was to provide a summary on recent developments in the field of sustainable sulfone synthesis. Advances and existing limitations in traditional approaches towards sulfones were reviewed on selected examples. Furthermore, novel emerging technologies for a more sustainable sulfone synthesis and future directions were discussed.

Synthesis and applications of sodium sulfinates (RSO2Na): a powerful building block for the synthesis of organosulfur compounds

This review highlights the preparation of sodium sulfinates (RSO2Na) and their multifaceted synthetic applications. Substantial progress has been made over the last decade in the utilization of sodium sulfinates emerging as sulfonylating, sulfenylating or sulfinylating reagents, depending on reaction conditions. Sodium sulfinates act as versatile building blocks for preparing many valuable organosulfur compounds through S-S, N-S, and C-S bond-forming reactions. Remarkable advancement has been made in synthesizing thiosulfonates, sulfonamides, sulfides, and sulfones, including vinyl sulfones, allyl sulfones, and β-keto sulfones. The significant achievement of developing sulfonyl radical-triggered ring-closing sulfonylation and multicomponent reactions is also thoroughly discussed. Of note, the most promising site-selective C-H sulfonylation, photoredox catalytic transformations and electrochemical synthesis of sodium sulfinates are also demonstrated. Holistically, this review provides a unique and comprehensive overview of sodium sulfinates, which summarizes 355 core references up to March 2020. The chemistry of sodium sulfinate salts is divided into several sections based on the classes of sulfur-containing compounds with some critical mechanistic insights that are also disclosed.

The fast and efficient KI/H2O2 mediated 2-sulfonylation of indoles and N-methylpyrrole in water

The rapid and efficient KI/H₂O₂-mediated 2-sulfonylation of substituted indoles and N-methylpyrrole was established. The corresponding 2-sulfonylation products are synthesized from readily available sulfur sources, namely arylsulfonyl hydrazides, 4-methylbenzenesulfinic acid and sodium 4-methylbenzenesulfinate in good to excellent yields in only 5 min. Moreover, the aqueous solution of hydrogen peroxide is used as both oxidant and solvent. Mechanistic studies demonstrated that 2,3-diiodoindoline was the main sulfonylation intermediate.

The rapid and efficient KI/H₂O₂-mediated 2-sulfonylation of substituted indoles and N-methylpyrrole was established.