Synthetic approaches and applications of sulfonimidates

Iron-Catalyzed Photochemical Synthesis of Sulfinamides from Aliphatic Hydrocarbons and Sulfinylamines

An iron-catalyzed photochemical sulfinamidation of hydrocarbons with N-sulfinylamines has been developed. The merger of ligand-to-metal charge transfer (LMCT) of FeCl3 with hydrogen atom transfer (HAT) process is the key for the generation of alkyl radicals from hydrocarbons, and the resultant alkyl radicals were readily trapped by N-sulfinylamines to produce structurally diverse sulfinamides. Contrary to traditional methods that inevitably use sensitive organometallic reagents and prefunctionalized substrates, our approach features simple operation and the wide availability of starting materials. Gratifyingly, the reaction is scalable, and the obtained sulfinamides can be conveniently converted to highly functionalized sulfur(VI) derivatives.

Asymmetric synthesis of sulfoximines, sulfonimidoyl fluorides and sulfonimidamides enabled by an enantiopure bifunctional S(VI) reagent

An increased interest to expand three-dimensional chemical space for the design of new materials and medicines has created a demand for isosteric replacement groups of commonly used molecular functionality. The structural and chemical properties of chiral S(VI) functional groups provide unique spatial and electronic features compared with their achiral sulfur- and carbon-based counterparts. Manipulation of the S(VI) centre to introduce structural variation with stereochemical control has remained a synthetic challenge. The stability of sulfonimidoyl fluorides and the efficiency of sulfur fluorine exchange chemistry has enabled the development of the enantiopure bifunctional S(VI) transfer reagent t-BuSF to overcome current synthetic limitations. Here, we disclose a reagent platform that serves as a chiral sulfur fluorine exchange template for the rapid asymmetric synthesis of over 70 sulfoximines, sulfonimidoyl fluorides and sulfonimidamides with excellent enantiomeric excess and good overall yields. Furthermore, the practical utility of the bifunctional S(VI) transfer reagent was demonstrated in the syntheses of enantiopure pharmaceutical intermediates and analogues.

Synthesis of sulfinamides via photocatalytic alkylation or arylation of sulfinylamine

Sulfinamides are a versatile class of compounds that find applications in both organic synthesis and pharmaceuticals. Here we developed an efficient photocatalytic approach for the convenient preparation of sulfinamides. Commercially available potassium trifluoro(organo)borates and readily available sulfinyl amines are rationally used and converted to a series of alkyl or aryl sulfinamides in moderate to high yields. The reaction allows for the gram-scale preparation of sulfinamides. Moreover, sulfonimidamides, sulfonimidate esters and sulfonyl amides could be obtained in one pot.

Progress in the Enantioselective Synthesis of Sulfur (VI) Compounds

In recent years, there has been a notable surge in the prominence of enantioenriched sulfur(VI) compounds within the chemical science, particularly in the realm of bioactive molecules. However, the synthesis of these enantioenriched sulfur(VI) compounds has posed significant challenges, necessitating the exploration of diverse synthetic methods. Accordingly, this review aims to provide an in-depth analysis of the latest advancements in the synthesis of sulfoximines, sulfonimidate esters, sulfonimidamides, and sulfonimidoyl halides, with a focus on developments since 1971.

Ph3P-mediated decarboxylative ring-opening of maleic anhydride by thiolic compounds: formation of two carbon-sulfur bonds

In this study, a simple and efficient method for the formation of carbon-sulfur bonds is described. In this process, ring opening of maleic anhydride by thiols or disulfides and triphenylphosphine led to the formation of sulfide products via formation of two carbon-sulfur bonds.

One-Pot Tandem Oxidative Bromination and Amination of Sulfenamide for the Synthesis of Sulfinamidines

The sulfinamidines as aza analogues of sulfinamides received limited attention from both organic chemists and pharmaceutical chemists. Herein, we present a tandem oxidative/nucleophilic substitution approach for the synthesis of sulfinamidines in high yield (up to 98%). This cascade reaction method is enabled by N-bromosuccinimide (NBS) as an oxidant and diverse readily available amines as nucleophiles without any additives or catalysts. Notably, this method is highly time-economical, safe to operate, and easy to scale up and has excellent functional group compatibility.

Synthesis of Chiral Sulfonimidoyl Chloride via Desymmetrizing Enantioselective Hydrolysis

Direct construction of chiral S(VI) from prochiral S(II) is a formidable challenge due to the inevitable formation of stable chiral S(IV). Previous synthetic strategies rely on the conversion of chiral S(IV) or enantioselective desymmetrization of preformed symmetrical S(VI) substrates. Here, we report desymmetrizing enantioselective hydrolysis of in situ-generated symmetric aza-dichlorosulfonium from sulfenamides for the preparation of chiral sulfonimidoyl chlorides, which could be used as a general stable synthon for obtaining a series of chiral S(VI) derivatives.

Synthesis of Sulfoximines and Sulfonimidamides Using Hypervalent Iodine Mediated NH Transfer

The development of NH transfer reactions using hypervalent iodine and simple sources of ammonia has facilitated the synthesis of sulfoximines and sulfonimidamides for applications across the chemical sciences. Perhaps most notably, the methods have been widely applied in medicinal chemistry and in the preparation of biologically active compounds, including in the large-scale preparation of an API intermediate. This review provides an overview of the development of these synthetic methods involving an intermediate iodonitrene since our initial report in 2016 on the conversion of sulfoxides into sulfoximines. This review covers the NH transfer to sulfoxides and sulfinamides, and the simultaneous NH/O transfer to sulfides and sulfenamides to form sulfoximines and sulfonimidamides, respectively. The mechanism of the reactions and the identification of key intermediates are discussed. Developments in the choice of reagents, and in the reaction conditions and setups used are described.

(1R,2S,5R)-2-Isopropyl-5-methylcyclohexyl (R)-4-methylbenzenesulfonimidate

(1R,2S,5R)-2-isopropyl-5-methylcyclohexyl (R)-4-methylbenzenesulfonimidate was synthesized via the stereoselective NH-transfer to (1R,2S,5R)-2-isopropyl-5-methylcyclohexyl (S)-4-methylbenzenesulfinate. The reaction employed diacetoxyiodobenzene (DIB) and ammonium carbamate, and occurred in acetonitrile at room temperature. The imidation of sulfur proceeded with complete stereocontrol, and the reaction afforded the desired product as a single diastereoisomer and with high enantiocontrol (e.r. = 97:3) in 70% yield. The product was characterized by 1H-NMR, 13C-NMR, COSY, HSQC, IR spectroscopy, HRMS, and the enantiomeric ratio was established by HPLC analysis at the chiral stationary phase.

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.

Stereospecific reaction of sulfonimidoyl fluorides with Grignard reagents for the synthesis of enantioenriched sulfoximines

Sulfonimidoyl halides have previously shown poor stability and selectivity in reaction with organometallic reagents. Here we report the preparation of enantioenriched sulfonimidoyl fluorides and their stereospecific reaction at sulfur with Grignard reagents. Notably the first enantioenriched alkyl sulfonimidoyl fluorides are prepared, including methyl. The nature of the N-group is important to the success of the stereocontrolled sequence to sulfoximines.

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.

Synthesis and Transformations of NH-Sulfoximines

Recent years have seen a marked increase in the occurrence of sulfoximines in the chemical sciences, often presented as valuable motifs for medicinal chemistry. This has been prompted by both pioneering works taking sulfoximine containing compounds into clinical trials and the concurrent development of powerful synthetic methods. This review covers recent developments in the synthesis of sulfoximines concentrating on developments since 2015. This includes extensive developments in both S-N and S-C bond formations. Flow chemistry processes for sulfoximine synthesis are also covered. Finally, subsequent transformations of sulfoximines, particularly in N-functionalization are reviewed, including N-S, N-P, N-C bond forming processes and cyclization reactions.

Syntheses and Transformations of Sulfinamides

Sulfinamides, especially enantiopure sulfinamides, are widely used in organic and medicinal synthesis. Syntheses and transformations of racemic and enantioenriched sulfinamides have achieved great progress. Especially sulfinamides demonstrate interesting and valuable reactivity, which deserves to be pertinent. This review summarizes the latest development in the synthesis and transformation of sulfinamides and will be helpful for future related research.

1 Introduction

2 Synthesis of Sulfinamides

2.1 Synthesis of Racemic Sulfinamides

2.2 Synthesis of Enantiomerically Pure Sulfinamides

2.3 Synthesis of Other Sulfinamides

3 Transformations of Sulfinamides

3.1 Condensation with Aldehydes and Ketones

3.2 Reaction with Alkynes

3.3 Reaction with Alkenes

3.4 Reaction with Aryl and Alkyl Halides

3.5 Reaction with Alcohols, Dibenzyl Ether, and Benzyl Mercaptan

3.6 Synthesis of tert-Butyldisulfanyl-Substituted Hetarenes

3.7 Synthesis of Asymmetric Sulfides

3.8 Synthesis of N-Phosphino-sulfinamide Ligands

3.9 Asymmetric Synthesis of γ-Amino Acids

3.10 Sulfonylation of Heterocyclic Compounds

4 Summary and Outlook

Silver-Catalyzed Enantioselective Sulfimidation Mediated by Hydrogen Bonding Interactions

An enantioselective sulfimidation of 3-thiosubstituted 2-quinolones and 2-pyridones was achieved with a stoichiometric nitrene source (PhI=NNs) and a silver-based catalyst system. Key to the success of the reaction is the use of a chiral phenanthroline ligand with a hydrogen bonding site. The enantioselectivity does not depend on the size of the two substituents at the sulfur atom but only on the binding properties of the heterocyclic lactams. A total of 21 chiral sulfimides were obtained in high yields (44-99 %) and with significant enantiomeric excess (70-99 % ee). The sulfimidation proceeds with high site-selectivity and can also be employed for the kinetic resolution of chiral sulfoxides. Mechanistic evidence suggests the intermediacy of a heteroleptic silver complex, in which the silver atom is bound to one molecule of the chiral ligand and one molecule of an achiral 1,10-phenanthroline. Support for the suggested reaction course was obtained by ESI mass spectrometry, DFT calculations, and a Hammett analysis.