The Synthesis of Trifluoromethyl-sulfonimidamides from Sulfinamides

Perfluorooxosulfate Salts as SOF4-Gas-Free Precursors to Multidimensional SuFEx Electrophiles

Sulfur(VI) Fluoride Exchange (SuFEx) chemistry stands as a well-established method for swiftly constructing complex molecules in a modular fashion. An especially promising segment of this toolbox is reserved for multidimensional SuFEx hubs: three or more substituents pluggable into a singular SVI centre to make 'beyond-linear' clicked constructions. Sulfurimidoyl difluorides (RNSOF2) stand out as the prime example of this, however their preparation from the scarcely available thionyl tetrafluoride (SOF4) limits this chemistry to only a few laboratories with access to this gas. In this work, we identify silver pentafluorooxosulfate (AgOSF5) as a viable SuFEx hub with reactivity equal to SOF4. The AgF2-mediated oxidation of SOCl2 gives rise to the hexacoordinate AgOSF5 adduct, which in contact with primary amines produces the sulfurimidoyl fluorides in high yields. In addition, we have found this workflow to be fully extendable to the trifluoromethyl homologue, AgOSF4CF3, and we propose the use of AgOSF4X salts as a general route to azasulfur SuFEx electrophiles from commercial starting materials.

A Sulfur Monoxide Surrogate Designed for the Synthesis of Sulfoxides and Sulfinamides

Sulfur monoxide (SO) is a highly reactive species that cannot be isolated in bulk. However, SO can play a pivotal role as a fundamental building block in organic synthesis. Reported herein is the design and application of a sulfinylhydrazine reagent as an easily prepared sulfur monoxide surrogate. We show facile thermal SO transfer from this reagent to dienes where a reaction using a mechanistic probe suggests the generation of singlet SO. Combined with Grignard reagents and appropriate carbon or nitrogen electrophiles, the reagent serves as an effective "SO" donor to enable the one-pot, three-component synthesis of sulfoxides and sulfinamides.

A Sulfoxide Reagent for One-Pot, Three-Component Syntheses of Sulfoxides and Sulfinamides

Sulfoxides and sulfinamides represent versatile sulfur functional groups found in ligands, chiral auxiliaries, and bioactive molecules. Canonical two-component syntheses, however, rely on substrates with a preinstalled C-S bond and impede efficient and modular access to these sulfur motifs. Herein is presented the application of an easily prepared, bench-stable sulfoxide reagent for one-pot, three-component syntheses of sulfoxides and sulfinamides. The sulfoxide reagent donates the SO unit upon the reaction with a Grignard reagent (RMgX) as a sulfenate anion (RSO^- ). While subsequent trapping reactions of this key intermediate with carbon electrophiles provide sulfoxides, a range of tertiary, secondary, and primary sulfinamides can be prepared by substitution reactions with electrophilic amines. The syntheses of sulfinamide analogs of amide- and sulfonamide-containing drugs illustrate the utility of the method for the rapid preparation of medicinally relevant molecules.

Copper-Catalyzed, Aerobic Synthesis of NH-Sulfonimidamides from Primary Sulfinamides and Secondary Amines

NH-Sulfonimidamides are prepared by copper-catalyzed coupling of primary sulfinamides with secondary amines. Neither a ligand nor an additive is needed, and air is the terminal oxidant. The reactions occur at room temperature, show good functional group tolerance, and lead to products in good yields. A sulfanenitrile is proposed as an intermediate in this oxidative amination.

Sulfonimidamides by Sequential Mechanochemical Chlorinations and Aminations of Sulfinamides

Here, we report the first mechanochemical synthesis of sulfonimidamides. The one-pot, two-step method requires neither a solvent nor inert conditions. In a mixer mill, sulfinamides are rapidly converted to sulfonimidoyl chlorides by oxidative chlorination with N-chlorosuccinimide (NCS). Subsequent substitutions with amines provides a wide range of diversely substituted sulfonimidamides.

A Silyl Sulfinylamine Reagent Enables the Modular Synthesis of Sulfonimidamides via Primary Sulfinamides

A new N-silyl sulfinylamine reagent allows the rapid preparation of a broad range of (hetero)aryl, alkenyl, and alkyl primary sulfinamides, using Grignard, organolithium, or organozinc reagents to introduce the carbon fragment. Treatment of these primary sulfinamides with an amine in the presence of a hypervalent iodine reagent leads directly to NH-sulfonimidamides. This two-step sequence is straightforward to perform and provides a modular approach to sulfonimidamides, allowing ready variation of both reaction components, including primary and secondary amines.

Direct synthesis of sulfenamides, sulfinamides, and sulfonamides from thiols and amines

Needless to say that organosulfur compounds with sulfur–nitrogen bonds have found various applications in diverse fields such as pharmaceuticals, agrochemicals, polymers, and so forth. Three major groups of such compounds are sulfenamides, sulfinamides, and sulfonamides which have been widely applied as building blocks in medical chemistry. Owing to their significant role in drug design and discovery programs, the search for and development of efficient, environmentally friendly, and economic processes for the preparation of the title compounds is of great importance in the pharmaceutical industry. Recently, oxidative coupling of thiols and amines, two readily available low-cost commodity chemicals, has emerged as a highly useful method for synthesizing structurally diverse sulfenamides, sulfinamides, and sulfonamides in a single step. Since this strategy does not require additional pre-functionalization and de-functionalization steps, it considerably streamlines synthetic routes and substantially reduces waste generation. This review will focus on recent advances and achievements in this attractive research arena.

This review provides a concise overview of the synthesis of biologically and synthetically valuable sulfenamide, sulfinamide, and sulfonamide derivatives through the direct oxidative coupling of readily available low-cost thiols and amines.

Rapid Access to N-Protected Sulfonimidoyl Fluorides: Divergent Synthesis of Sulfonamides and Sulfonimidamides

Herein we report a practical and efficient copper-catalyzed approach for the conversion of various arenediazonium salts to the corresponding N-protected sulfonimidoyl fluorides. This operationally simple protocol tolerates a wide range of functional groups and can be applied to the late-stage modification of complex bioactive molecules. Furthermore, pharmaceutically important primary sulfonamides and sulfonimidamides derived from these valuable N-protected sulfonimidoyl fluoride units were prepared in minimal synthetic steps.

Synthetic approaches and applications of sulfonimidates

This review article explores the synthesis of the organosulfur(vi) species named sulfonimidates, focusing on their synthesis from sulfur(ii), sulfur(iv) and sulfur(vi) reagents, and investigates their recent resurgeance in interest as intermediates to access other important organosulfur compounds. Sulfonimidates have been utilized as precursors for polymers, sulfoximine and sulfonimidamide drug candidates and as alkyl transfer reagents.

Harnessing Sulfinyl Nitrenes: A Unified One-Pot Synthesis of Sulfoximines and Sulfonimidamides

Sulfoximines and sulfonimidamides are promising compounds for medicinal and agrochemistry. As monoaza analogues of sulfones and sulfonamides, respectively, they combine good physicochemical properties, high stability, and the ability to build complexity from a three-dimensional core. However, a lack of quick and efficient methods to prepare these compounds has hindered their uptake in molecule discovery programmes. Herein, we describe a unified, one-pot approach to both sulfoximines and sulfonimidamides, which exploits the high electrophilicity of sulfinyl nitrenes. We generate these rare reactive intermediates from a novel sulfinylhydroxylamine (R–O–N=S=O) reagent through an N–O bond fragmentation process. Combining sulfinyl nitrenes with carbon and nitrogen nucleophiles enables the synthesis of sulfoximines and sulfonimidamides in a reaction time of just 15 min. Alkyl, (hetero)aryl, and alkenyl organometallic reagents can all be used as the first or second component in the reaction, while primary and secondary amines, and anilines, all react with high efficiency as the second nucleophile. The tolerance of the reaction to steric and electronic factors has allowed for the synthesis of the most diverse set of sulfoximines and sulfonimidamides yet described. Experimental and computational investigations support the intermediacy of sulfinyl nitrenes, with nitrene formation proceeding via a transient triplet intermediate before reaching a planar singlet species.

Modern Stereoselective Synthesis of Chiral Sulfinyl Compounds

Chiral sulfinyl compounds, sulfoxides, sulfoximines, sulfinamides, and other derivatives, play an important role in asymmetric synthesis as versatile auxiliaries, ligands, and catalysts. They are also recognized as pharmacophores found in already marketed and well-sold drugs (e.g., esomeprazole) and used in drug design. This review is devoted to the modern methods of preparation of sulfinyl derivatives in enantiopure or enantiomerically enriched form. Selected new approaches leading to racemic products for which the asymmetric variant can be developed in the future are mentioned as well.

Additions to N-Sulfinylamines as an Approach for the Metal-free Synthesis of Sulfonimidamides: O-Benzotriazolyl Sulfonimidates as Activated Intermediates

Sulfonimidamides are obtained in moderate to very good yields from the key intermediates O-benzotriazolyl sulfonimidates, which are formed by reacting aryldiazonium tetrafluoroborates, N-tritylsulfinylamine, and N-hydroxybenzotriazole hydrate in a process mediated by a tertiary amine. The formation of the sulfonimidate proceeds in inexpensive and environmentally benign dimethyl carbonate as the solvent, it does not require anhydrous conditions, and the product yields generally exceed 70 %. The substrate scope is broad, and a wide range of sensitive organic functionalities is well tolerated. The reactions probably proceed via aryl radicals formed from diazonium cations with assistance from both the tertiary amine and the sulfinylamine.

Modular Sulfondiimine Synthesis Using a Stable Sulfinylamine Reagent

Sulfondiimines—the double aza-analogues of sulfones—hold significant potential as leads in discovery chemistry, yet their application in this arena has been held back by the scarcity of appropriate synthetic routes. Existing methods employ sulfides as substrates, and rely on consecutive imination reactions using the hazardous reagent O-mesitylenesulfonyl hydroxylamine. Here we report a method for sulfondiimine synthesis that does not begin with a sulfide or a thiol, and instead employs two Grignard reagents and a bespoke sulfinylamine (R—N=S=O) reagent as starting materials. Lewis acid-mediated assembly of these three components provides efficient access to a series of sulfilimine intermediates. A novel rhodium-catalyzed imination of these electron-rich sulfilimines then delivers a varied range of sulfondiimines featuring orthogonal N-functionalization. Conditions for the selective manipulation of both N-atoms of the sulfondiimines are reported, allowing access to a broad range of mono- and difunctionalized products. The oxidation of the sulfilimine intermediates is also described, and provides a complementary route to sulfoximines.

Regioselective and oxidant-free sulfinylation of indoles and pyrroles with sulfinamides

An unexpected time-controlled highly selective C3- or C2-sulfinylation of pyrroles with sulfinamides is reported for the first time. The sulfinylation of indoles with sulfinamides using this protocol is oxidant-free and can be performed under obviously more feasible conditions (1.2 equiv. of indoles, 10 min) in comparison with the precedent procedure (3-20 equiv. of indoles, 16-18 h, ammonium persulfate as oxidant, hv). A variety of functional groups were tolerated, and various C2-thioindoles and C2/3-thiopyrroles were obtained in moderate to excellent yields.

Exploration of Novel Chemical Space: Synthesis and in vitro Evaluation of N-Functionalized Tertiary Sulfonimidamides

An unprecedented set of structurally diverse sulfonimidamides (47 compounds) has been prepared by various N-functionalization reactions of tertiary =NH sulfonimidamide 2 aa. These N-functionalization reactions of model compound 2 aa include arylation, alkylation, trifluoromethylation, cyanation, sulfonylation, alkoxycarbonylation (carbamate formation) and aminocarbonylation (urea formation). Small molecule X-ray analyses of selected N-functionalized products are reported. To gain further insight into the properties of sulfonimidamides relevant to medicinal chemistry, a variety of structurally diverse reaction products were tested in selected in vitro assays. The described N-functionalization reactions provide a short and efficient approach to structurally diverse sulfonimidamides which have been the subject of recent, growing interest in the life sciences.

SuFEx Chemistry of Thionyl Tetrafluoride (SOF4 ) with Organolithium Nucleophiles: Synthesis of Sulfonimidoyl Fluorides, Sulfoximines, Sulfonimidamides, and Sulfonimidates

Thionyl tetrafluoride (SOF4 ) is a valuable connective gas for sulfur fluoride exchange (SuFEx) click chemistry that enables multidimensional linkages to be created via sulfur-oxygen and sulfur-nitrogen bonds. Herein, we expand the available SuFEx chemistry of SOF4 to include organolithium nucleophiles, and demonstrate, for the first time, the controlled projection of sulfur-carbon links at the sulfur center of SOF4 -derived iminosulfur oxydifluorides (R1 -N=SOF2 ). This method provides rapid and modular access to sulfonimidoyl fluorides (R1 -N=SOFR2 ), another array of versatile SuFEx connectors with readily tunable reactivity of the S-F handle. Divergent connections derived from these valuable sulfonimidoyl fluoride units are also demonstrated, including the synthesis of sulfoximines, sulfonimidamides, and sulfonimidates.

CF3SO2X (X = Na, Cl) as reagents for trifluoromethylation, trifluoromethylsulfenyl-, -sulfinyl- and -sulfonylation. Part 1: Use of CF3SO2Na

Sodium trifluoromethanesulfinate, CF3SO2Na, and trifluoromethanesulfonyl chloride, CF3SO2Cl, are two popular reagents that are widely used for the direct trifluoromethylation of a large range of substrates. Further, these two reagents are employed for the direct trifluoromethylsulfenylation and trifluoromethylsulfinylation, the introduction of the SCF3 and the S(O)CF3 group, respectively. In addition to the aforementioned reactions, the versatility of these two reagents is presented in other reactions such as sulfonylation and chlorination. This first part is dedicated to sodium trifluoromethanesulfinate.