Efficient synthesis of unsymmetrical sulfamides from sulfamic acid salts by activation with triphenylphosphine ditriflate

Palladium-Catalyzed Remote Hydrosulfonamidation of Alkenes: Access to Primary N-Alkyl Sulfamides by the SuFEx Reaction

Herein, we establish a remote hydrosulfonamidation (HSA) of alkenes using palladium catalysis, where N-fluoro-N-(fluoro-sulfonyl)-carbamate with a sulfur(VI) fluoride moiety is demonstrated as a good amidation reagent. The anti-Markovnikov HSA reaction of terminal alkenes and the remote HSA of internal alkenes are achieved to efficiently yield primary N-alkyl-N-(fluorosulfonyl)-carbamates. In addition, this protocol enables the high-value utilization of alkane by combining the dehydrogenation process. The generated N-alkyl products exhibit a unique reactivity of sulfur(VI) fluorides, which can be directly transferred to N-alkyl sulfamides or amines via the sulfur(VI) fluoride exchange reaction, thereby streamlining their synthesis. Moreover, a (pyridyl) benzazole-type ligand proved to be vital for the excellent chemo- and regioselectivities.

One-Flow Syntheses of Unsymmetrical Sulfamides and N-Substituted Sulfamate Esters

We developed one-flow syntheses of unsymmetrical sulfamides and N-substituted sulfamate esters by changing a nucleophile and a tertiary amine from inexpensive and commercially available chlorosulfonic acid. In the synthesis of N-substituted sulfamate esters, unexpected symmetrical sulfite formation was suppressed by changing the tertiary amine. The effect of tertiary amines was proposed using linear regression. Our approach rapidly (≤90 s) provides desired products containing acidic and/or basic labile groups without tedious purification under mild (20 °C) conditions.

Strategies to Generate Nitrogen-centered Radicals That May Rely on Photoredox Catalysis: Development in Reaction Methodology and Applications in Organic Synthesis

For more than 70 years, nitrogen-centered radicals have been recognized as potent synthetic intermediates. This review is a survey designed for use by chemists engaged in target-oriented synthesis. This review summarizes the recent paradigm shift in access to and application of N-centered radicals enabled by visible-light photocatalysis. This shift broadens and streamlines approaches to many small molecules because visible-light photocatalysis conditions are mild. Explicit attention is paid to innovative advances in N-X bonds as radical precursors, where X = Cl, N, S, O, and H. For clarity, key mechanistic data is noted, where available. Synthetic applications and limitations are summarized to illuminate the tremendous utility of photocatalytically generated nitrogen-centered radicals.

Synthesis of unsymmetrical sulfamides and polysulfamides via SuFEx click chemistry

As hydrogen-bond donors and acceptors, N,N'-disubstituted sulfamides have been used in a range of applications from medicinal chemistry to anion-binding catalysis. However, compared to ureas or thioureas, the utilization of this unique moiety remains marginal, in part because of a lack of general synthetic methods to access unsymmetrical sulfamides. Specifically, polysulfamides are a virtually unknown type of polymer despite their potential utility in non-covalent dynamic networks, an intense area of research in materials science. We report herein a practical and efficient process to prepare unsymmetrical sulfamides via Sulfur(vi)-Fluoride Exchange (SuFEx) click chemistry. This process was then applied to synthesize polysulfamides. Thermal analysis showed that this family of polymers possess high thermal stability and tunable glass transition temperatures. Finally, hydrolysis studies indicated that aromatic polysulfamides could be recycled back to their constituting monomers at the end of their life cycle.

Photochemically Mediated Nickel-Catalyzed Synthesis of N-(Hetero)aryl Sulfamides

A general method for the N-arylation of sulfamides with aryl bromides is described. The protocol leverages a dual-catalytic system, with [Ir(ppy)2(dtbbpy)]PF6 as a photosensitizer, NiBr2·glyme as a precatalyst, and 1,8-diazabicyclo(5.4.0)undec-7-ene (DBU) as a base, and proceeds at room temperature under visible light irradiation. Using these tactics, aryl boronic esters and aryl chlorides can be carried through the reaction untouched. The developed reactions efficiently engage simple bromoarenes and primary sulfamides in between 66% and quantitative yields. For more challenging substrates, such as secondary sulfamides, the reaction efficiency is documented. Thereby, these methods complement the known Buchwald-Hartwig coupling methods for N-arylation of sulfamides.

Sulfamides direct radical-mediated chlorination of aliphatic C-H bonds

Given the prevalence of aliphatic amines in bioactive small molecules, amine derivatives are opportune as directing groups. Herein, sulfamides serve as amine surrogates to guide intermolecular chlorine-transfer at γ-C(sp³) centers. This unusual position-selectivity arises because accessed sulfamidyl radical intermediates engage preferentially in otherwise rare 1,6-hydrogen-atom transfer (HAT) processes through seven-membered transition states. The site-selectivity of C–H abstraction can be modulated by adjusting the steric and electronic properties of the sulfamide nitrogen substituents, an ability that has not been demonstrated with other substrate classes. The disclosed reaction relies on a light-initiated radical chain-propagation mechanism to oxidize C(sp³)–H bonds efficiently.

Amine-anchored sulfamides direct radical-mediated chlorination of aliphatic C–H bonds. The site of C–H abstraction can be modulated by varying the sulfamide nitrogen substituents, a feature that has not been demonstrated with other substrate classes.