Turn formation initiated by a bissulfoximine motif: synthesis and structural investigation

Facile synthesis of N-(α-furanyl) alkyl sulfoximines via gold catalyzed Michael addition/cyclization of enynones and sulfoximines

Herein, we prepare a new array of N-(α-furanyl) alkyl sulfoximines via a gold catalyzed reaction of enynone with sulfoximine in moderate to very good yields. The reaction involves Michael addition of sulfoximine to enynone, followed by intramolecular cyclization. The presence of two chiral centres led to the formation of a mixture of diastereomers approximately in a 1 : 1 ratio. The salient features of the protocol include broad substrate scope, high efficiency and high yields. The synthetic utility of the protocol is explored using Suzuki-Miyaura cross-coupling and mild, metal-free opening of the furan ring.

Silver-mediated Room Temperature Reactions for the Synthesis of N-α-Ketoacyl Sulfoximines and N-α,β-Unsaturated Acyl Sulfoximines

Here, we report a silver-mediated coupling of acetylenes with sulfoximines to synthesize N-α-ketoacyl sulfoximines and N-α,β-unsaturated acyl sulfoximines. The reactions are performed under an open atmosphere using the oxidant K₂S₂O₈ and the ligand 2,2-bipyridyl. However, the fate of the product formation is controlled by the type of substrate used. The coupling between aryl acetylenes and sulfoximines afforded the N-α-ketoacylsulfoximines, while the alkyl acetylenes provided the N-α,β-unsaturated acyl sulfoximines. Controlled experiments reveal the differential reactivity patterns of substrates. The labeling ¹⁸O experiments showed that water is the source of the incoming oxygen atom for the keto group of N-α-ketoacyl sulfoximines and N-α,β-unsaturated acyl sulfoximines.

One-pot synthesis of α-sulfoximinophosphonate via Kabachnik-Fields reaction

Herein, we disclose a novel approach for the synthesis of hitherto unknown α-sulfoximinophosphonate via the Kabachnik-Fields reaction of aldehyde, dialkylphosphite and sulfoximine in the presence of InCl₃ in THF at 70 °C. α-Sulfoximinophosphonate is synthesized in good yields and its synthetic utilities are proved by functionalizing bromine through the Pd-catalyzed Suzuki-Miyaura cross-coupling reaction and reduction of a nitro group through the Béchamp reduction.

A metal-free Petasis reaction towards the synthesis of N-(α-substituted)alkyl sulfoximines/sulfonimidamides

Herein, we disclose a metal-free novel approach for the synthesis of N-(α-substituted)alkyl sulfoximines/sulfonimidamides via one-pot multicomponent Petasis reactions of aryl boronic acids, ortho-hydroxyarylaldehydes and sulfoximines/sulfonimidamides in moderate to very good yields. The presence of two chiral centres provides a mixture of diastereomers almost in a 1 : 1 ratio, which are separated successfully in most of the cases. The -OH functionality of Petasis products is further utilized to derive heterocycles via O-allylation, followed by intramolecular Heck cyclization, proving the synthetic utility of the products.

An efficient imidation of thioethers with nitrene in water

The first imidation of thioethers with free nitrene in water was realized. N-Cbz sulfilimines are formed via imidation of thioethers with free nitrene generated from α elimination of nosyloxycarbamates. In this work, water is successfully applied as solvent for free nitrene, and transition metal catalyst is not needed.

Direct N-acylation of sulfoximines with carboxylic acids catalyzed by the B3NO2 heterocycle

Dehydrative coupling of sulfoximines and carboxylic acids is rendered catalytic by a heterocyclic catalyst featuring the B₃NO₂ ring system.

Metal-Free, Phosphonium Salt-Mediated Sulfoximination of Azine N-Oxides: Approach for the Synthesis of N-Azine Sulfoximines

Herein, we report a simple and metal-free method for the synthesis of N-azine sulfoximines by the nucleophilic substitution of azine N-oxides with NH-sulfoximines. The present method works at room temperature with wide functional group compatibility and gives several unprecedented N-azine sulfoximines. The reaction conditions were also found suitable with enantiopure substrates and furnished products without any racemization. It also finds an application in the sulfoximination of azine-based functional molecules such as 2,2'-bipyridine, 1,10-phenanthroline, and quinine.

Synthesis of chiral sulfoximine-based thioureas and their application in asymmetric organocatalysis

For the first time, chiral sulfoximine derivatives have been applied as asymmetric organocatalysts. In combination with a thiourea-type backbone the sulfonimidoyl moiety leads to organocatalysts showing good reactivity in the catalytic desymmetrization of a cyclic meso-anhydride and moderate enantioselectivity in the catalytic asymmetric Biginelli reaction. Straightforward synthetic routes provide the newly designed thiourea-sulfoximine catalysts in high overall yields without affecting the stereohomogeneity of the sulfur-containing core fragment.

Comparative Study of Metal-Catalyzed Iminations of Sulfoxides and Sulfides

A comparative study of the imination of sulfur compounds with various metal catalysts in combination with isolated or in situ generated iminoiodinanes (PhI==NR) as nitrogen sources is presented. The influence of the metal catalyst towards the imination of a variety of substituted sulfoxides has been evaluated. Moreover, the effect of the different oxidation states of sulfur on the reactivity and selectivity of the nitrogen transfer redox process in the formation of sulfilimines and sulfoximines was studied. Depending on both the specific metal catalyst as well as the employed nitrene precursor, the sulfide/sulfoxide imination ratio varied in transformations of thianthrene-5-oxide and substituted para-thio phenylsulfoxides.

Highly modular synthesis of C1-symmetric aminosulfoximines and their use as ligands in copper-catalyzed asymmetric Mukaiyama-aldol reactions

The development of C1-symmetric aminosulfoximines, their highly modular synthesis, and their application in enantioselective copper-catalyzed Mukaiyama-type aldol reactions between pyruvates and enolsilanes is described. In this context, the influence of the ligand architecture as well as the optimization of the reaction conditions are discussed. In detail, the dependence of the catalyst efficiency on the solvent, the metal source and the temperature are reported, and an interesting additive effect is highlighted. Furthermore, the substrate scope will be presented. With the optimized catalyst system, a number of aldol products with quaternary stereogenic centers have been obtained in high yields and with enantiomeric excesses up to 99 %.

Efficient copper-catalyzed N-arylation of sulfoximines with aryl iodides and aryl bromides

Two simple and inexpensive systems for copper-catalyzed N-arylations of sulfoximines with aryl bromides and aryl iodides have been developed. Using 10 mol % of a copper(I) salt in combination with 20 mol % of a 1,2-diamine and Cs2CO3 provides N-arylated sulfoximines in high yields. Various functional groups and heteroatoms are tolerated. The method is complementary to the known protocols for N-arylations of sulfoximines, which require stoichiometric quantities of copper salts or cost-intensive palladium/BINAP catalysts.

Iron-Catalyzed Imination of Sulfoxides and Sulfides

[reaction: see text] The Fe(III)-catalyzed imination of sulfoxides and sulfides with sulfonylamides in the presence of iodinanes has been investigated. The best results were obtained when Fe(acac)(3) was used as a catalyst in combination with iodosylbenzene, providing an effective alternative (stereospecific) access to sulfoximines and sulfilimines.

Silver-Catalyzed Imination of Sulfoxides and Sulfides

[reaction: see text] Silver salts in the presence of a chelating ligand efficiently catalyze the stereospecific imination of sulfoxides and sulfides with sulfonylamides and PhI(OAc)(2) to afford sulfoximines and sulfilimines, respectively, in good yields.

Palladium-Catalyzed α-Arylation of Sulfoximines

[reaction: see text] Palladium-catalyzed alpha-arylation of N-benzoyl sulfoximine ethyl ester with various aryl bromides leads to alpha-arylated products that can easily be hydrolyzed, giving the corresponding N-protected benzyl phenyl sulfoximines. In this manner, new sulfoximine derivatives are accessible that have so far been difficult to prepare in enantiopure form.

Synthesis and Palladium-Catalyzed Coupling Reactions of Enantiopure p-Bromophenyl Methyl Sulfoximine

[reaction: see text] The asymmetric synthesis and chemical modification of p-bromophenyl methyl sulfoximine (2) is described. Starting from p-bromophenyl menthyl sulfinate (5), enantiopure 2 can be obtained in a short reaction sequence involving a well-established substitution reaction followed by stereospecific imination with O-mesitylenesulfonylhydroxylamine (MSH). Palladium-catalyzed Buchwald/Hartwig, Suzuki, and Stille coupling reactions allow a broad variation of the sulfoximine aryl group, which is otherwise difficult to achieve. The incorporation of a p-morpholino-substituted derivative into a pseudotripeptide demonstrates the applicability of the novel sulfoximine derivatives.

Copper-Mediated Cross-Coupling Reactions of N-Unsubstituted Sulfoximines and Aryl Halides

[reaction: see text] Copper-mediated cross-coupling reactions of sulfoximines with aryl iodides and aryl bromides provide N-arylated sulfoximines in high yields. The method is complementary to the known palladium-catalyzed N-arylation and allows the preparation of N-arylated sulfoximines, which have previously been inaccessible.

Rhodium-Catalyzed Imination of Sulfoxides and Sulfides: Efficient Preparation of N-Unsubstituted Sulfoximines and Sulfilimines

The Rh(II)-catalyzed imination of sulfoxides and sulfides using [Rh(2)(OAc)(4)] as a catalyst and trifluoroacetamide or sulfonylamides in combination with iodobenzene diacetate and magnesium oxide affords sulfoximines and sulfilimines, respectively, in a stereospecific manner. [reaction: see text]

The stability of pseudopeptides bearing sulfoximines as chiral backbone modifying element towards proteinase K

Incorporation of sulfoximines as backbone modifying element results in two new pseudopeptide bonds which display enhanced (bond A) and strongly reduced reactivity (bond B) towards hydrolysis by Proteinase K.