Synthesis of Sulfondiimines byN-Chlorosuccinimide-Mediated Oxidative Imination of Sulfiliminium Salts

Diphenylphosphinylhydroxylamine (DPPH) Affords Late-Stage S-imination to access free-NH Sulfilimines and Sulfoximines

Sulfilimines, as potential aza-isosteres of sulfoxides, are valued as building blocks, auxiliaries, ligands, bioconjugation handles, and as precursors to versatile S(VI) scaffolds including sulfoximines and sulfondiimines. Here, we report a thioether imination methodology that exploits O-(diphenylphosphinyl)hydroxyl amine (DPPH). Under mild, metal-free, and biomolecule-compatible conditions, DPPH enables late-stage S-imination on peptides, natural products, and a clinically trialled drug, and shows both excellent chemoselectivity and broad functional group tolerance. This methodological report is extended to an efficient and high-yielding one-pot reaction for accessing free-NH sulfoximines with diverse substrates including ones of potential clinical importance. In the presence of a rhodium catalyst, sulfoxides are S-iminated in higher yields to afford free-NH sulfoximines. S-imination was validated on an oxidatively delicate amatoxin to give sulfilimine and sulfoximine congeners. Interestingly, these new sulfilimine and sulfoximine-amatoxins show cytotoxicity. This method is further extended to create sulfilimine and sulfoximine-Fulvestrant and buthionine analogues.

Modular Synthesis of 1,2-Benzothiazines and 1,2-Benzothiazine 1-Imines via Palladium-Catalyzed C-H/C-C Activation Reactions

In this study, a modular approach toward cyclic sulfoximines and sulfondiimines via palladium-catalyzed intramolecular C-H/C-C activation reactions was reported. Various 1,2-benzothiazines including bicyclic, tricyclic, highly fused ones, ones of the seven-membered ring, along with 1,2-benzothiazine 1-imines were accessed in good yields. KIE experiment demonstrated that the C-H bond cleavage at the position ortho to the sulfoximine group is not the rate-determining step in the coupling reaction.

Photocatalytic N-Alkylation of NH-Diaryl Sulfondiimines via Anti-Markovnikov Hydroamination with Styrenes

Sulfondiimines, which are isoelectronic with sulfones and sulfoximines, represent a neglected yet intriguing pharmacophore in the discovery program. Herein, we present a facile and mild photocatalytic anti-Markovnikov hydroamination of styrenes for the construction of N-alkylated sulfondiimines with primary, secondary, and tertiary alkyl substituents. A sulfondiimine-derived analogue of the marketed drug Vioxx was synthesized using this method as the key step.

Silver-Catalyzed Chlorocyclization for the Synthesis of 3-Chloro-2H-chromenes

A silver-catalyzed chlorocyclization reaction of aryl 3-aryl-2-propyn-1-yl ethers in the presence of NCS under darkness was accomplished, which provides a straightforward and efficient access to 3-chloro-2H-chromenes.

Synthesis of Sulfilimines via Selective S-C Bond Formation in Water

Sulfilimines are valuable compounds both in organic synthesis and in pharmaceuticals. Here we developed a mild and simplified method for preparation of sulfilimines via selective S-C bond formation rather than traditional S-N bond formation. The method is both attractive and useful for the following reasons: it uses a readily available alkylation reagent such alkyl bromide or alkyl iodide, it uses water as solvent, it is easy to perform, and it is convenient for late-stage diversification of drugs.

Dehydrogenative Imination of Low-Valent Sulfur Compounds-Fast and Scalable Synthesis of Sulfilimines, Sulfinamidines, and Sulfinimidate Esters

Herein, we describe an electrochemical pathway for the synthesis of sulfilimines, sulfoximines, sulfinamidines, and sulfinimidate esters from readily available low-valent sulfur compounds and primary amides or their analogues. The combination of solvents and supporting electrolytes together act both as an electrolyte as well as a mediator, leading to efficient use of reactants. Both can be easily recovered, enabling an atom-efficient and sustainable process. A broad scope of sulfilimines, sulfinamidines, and sulfinimidate esters with N-EWGs is accessed in up to excellent yields with broad functional group tolerance. This fast synthesis can be easily scaled up to multigram quantities with high robustness for fluctuation of current densities of up to 3 orders of magnitude. The sulfilimines are converted into the corresponding sulfoximines in an ex-cell process in high to excellent yields using electro-generated peroxodicarbonate as a green oxidizer. Thereby, preparatively valuable NH sulfoximines are accessible.

Sulfondiimines: synthesis, derivatisation and application

Sulfondiimines are aza-analogues of sulfones and sulfoximines. In contrast to the latter two compound classes, sulfondiimines are rare in the chemical literature. Although a full understanding of the stability and reactivity of sulfondiimines is wanting, sulfondiimines have recently been recognized as novel bioisosteres for carbonyl moieties enabling expansion of the well-known portfolio of pharmaceutically relevant compounds. In this review, we briefly summarize the structure and stability of sulfondiimines and then focus on syntheses and derivatisations of these interesting compounds with sulfur-nitrogen core units. Furthermore, their use in heterocyclic chemistry and recent applications as bioactive compounds are presented.

Synthesis of Pyrroles via Consecutive 6π-Electrocyclization/Ring-Contraction of Sulfilimines

We present a modular, synthetic entry to polysubstituted pyrroles employing readily available 2,5-dihydrothiophenes. Ring-opening of the heterocycle provides access to a panel of 1,3-dienes which undergo pyrrole formation in the presence of inexpensive chloramine-T trihydrate. The transformation is conducted in an open flask and proceeds at ambient temperatures (23 °C) in nondry solvents. A careful adjustment of the electronics and sterics of the 1,3-diene precursor allows for the isolation of key intermediates. DFT studies identified a reaction mechanism that features a 6π-electrocyclization of a sulfilimine intermediate followed by spontaneous ring-contraction to reveal the pyrrole skeleton.

Chiral Analogues of PFI-1 as BET Inhibitors and Their Functional Role in Myeloid Malignancies

Structural analogues of PFI-1 varying at the sulfur core were prepared, and their activities as BET inhibitors in myeloid cell lines and primary cells from patients with acute myeloid leukemia were studied. Docking calculations followed by molecular dynamics simulations revealed the binding mode of the newly prepared inhibitors, suggesting explanations for the observed high enantiospecificity of the inhibitory activity.

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.

Neglected sulfur(vi) pharmacophores in drug discovery: exploration of novel chemical space by the interplay of drug design and method development

The key learnings of the utilization of sulfoximines, sulfondiimines and sulfonimidamides in drug discovery at Bayer AG are shared.

Mechanistic investigation of the NH-sulfoximination of sulfide. Evidence for λ6-sulfanenitrile intermediates

One-pot synthesis of NH-sulfoximines from sulfides was reported through fully described acetoxy- and methoxy-λ⁶-sulfanenitrile intermediates (¹H, ¹³C, ¹⁵N NMR and HRMS).

Synthesis of NH-sulfoximines from sulfides by chemoselective one-pot N- and O-transfers

Direct synthesis of NH-sulfoximines from sulfides has been achieved through O and NH transfer in the same reaction, occurring with complete selectivity.

Access to N-cyanosulfoximines by transition metal-free iminations of sulfoxides

Sulfoxides are stereospecifically converted to N-cyanosulfoximines using N-chlorosuccinimide (NCS) as oxidising agent and cyanamide as nucleophilic amine source.

CFBSA: a novel and practical chlorinating reagent

A novel chlorinating reagent was synthesized from easily-obtained materials and it shows great reactivity to a large scope of substrates.