Transition-Metal-Free Reductive Cross-Coupling Employing Metabisulfite as a Connector: General Construction of Alkyl–Alkyl Sulfones

Palladium-Catalyzed Methylsulfonylation of Alkyl Halides Using Dimethyl Sulfite as SO2 Surrogate and Methyl Source

“…Initially, radical scavenger TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl, 5 equiv) was added to the model reaction, and trace amount of 3a was obtained, which implied that a radical process might be involved in the reaction (Scheme , eq 1). Subsequently, when (iodomethyl)­cyclopropane ( 4 ) was applied in the coupling reaction, the ring-opening product 3aa was isolated in 34% yield, which proved that radical coupling for C–S bond formation between alkyl and methylsulfonyl radical was involved in this methylsulfonylation (Scheme , eq 2) . On treatment of benzenesulfonyl iodide ( 5 ) with 2a under standard conditions, only 10% yield of target product 3b was afforded, which indicated that the intermediate 5 might not be involved in the reaction process (Scheme , eq 3).…”

“…Initially, the desulfurization of 2a in the presence of TBAB provides methyl radical and releases SO 2 . Subsequently, methyl radical reacts with SO 2 to furnish radical B , which further transforms to sulfonyl anion C via single electronic transfer process under the assistance of silane. Then, the reaction of sulfonyl anion C with palladium species A generates intermediate D .…”

Prospects and Challenges in Organosulfur Chemistry

“…Willis et al and Ye and Wu explored the insertion of the SO 2 motif in a three-component coupling reaction by using DABSO [DABCO·(SO 2 ) 2 ] as a sulfur dioxide surrogate, which was prepared by Santos and Mello in 1988 . Subsequently, several inorganic salts, such as sodium metabisulfite, , sodium dithionite, , and thiourea dioxide, , served as sulfur dioxide sources for the construction of sulfones. In these strategies, the SO 2 motif in inorganic sulfur salts possesses a sufficiently active hybridized SOMO to participate in a radical process.…”

Full-Spectrum Fluoromethyl Sulfonation via Modularized Multicomponent Coupling

“…[19][20][21][22][23][24][25][26][27][28][29] Based on the observed effect of sulfur introduction from inorganic salts, [30][31][32][33][34][35][36] sulfur dioxide surrogates possessing diverse masking groups with disparate properties have been explored for the construction of sulfones. [37][38][39][40][41][42][43][44][45] Thiourea dioxide, an industrial raw material a base. We envisioned the use of thiourea dioxide as both a sulfur dioxide source and a hydrogen bond donor due to the properties of the urea motif.…”