Organische N-Sulfinyl-Verbindungen

Kinetically-driven reactivity of sulfinylamines enables direct conversion of carboxylic acids to sulfinamides

Sulfinamides are some of the most centrally important four-valent sulfur compounds that serve as critical entry points to an array of emergent medicinal functional groups, molecular tools for bioconjugation, and synthetic intermediates including sulfoximines, sulfonimidamides, and sulfonimidoyl halides, as well as a wide range of other S(iv) and S(vi) functionalities. Yet, the accessible chemical space of sulfinamides remains limited, and the approaches to sulfinamides are largely confined to two-electron nucleophilic substitution reactions. We report herein a direct radical-mediated decarboxylative sulfinamidation that for the first time enables access to sulfinamides from the broad and structurally diverse chemical space of carboxylic acids. Our studies show that the formation of sulfinamides prevails despite the inherent thermodynamic preference for the radical addition to the nitrogen atom, while a machine learning-derived model facilitates prediction of the reaction efficiency based on computationally generated descriptors of the underlying radical reactivity.

Rediscovering Sulfinylamines as Reagents for Organic Synthesis

Sulfinylamines (R-N=S=O), monoaza analogues of sulfur dioxide, have been known for well over a century, and their reactivity as sulfur electrophiles and in Diels-Alder reactions is well-established. However, they have only rarely been used in organic synthesis in recent decades despite the increasing prominence of compounds containing N=S=O functionality, such as sulfoximines and sulfonimidamides. This Minireview aims to bring wider visibility to the unique chemistry enabled by this class of compounds. We focus on advances from the last 10 years, including the first examples of their use in the one-pot syntheses of sulfoximines and sulfonimidamides. Also covered are the reactions of sulfinylamines with carbon-centred radicals, their use for formation of heterocycles through cycloadditions, and catalytic enantioselective allylic oxidation of alkenes via a hetero-ene reaction. These examples highlight the different reactivity modes of sulfinylamines and their underappreciated potential for forming molecules which contain high- or low-valent sulfur, or even no sulfur at all.

Primary Sulfonamide Synthesis Using the Sulfinylamine Reagent N-Sulfinyl-O-(tert-butyl)hydroxylamine, t-BuONSO

Sulfonamides have played a defining role in the history of drug development and continue to be prevalent today. In particular, primary sulfonamides are common in marketed drugs. Here we describe the direct synthesis of these valuable compounds from organometallic reagents and a novel sulfinylamine reagent, t-BuONSO. A variety of (hetero)aryl and alkyl Grignard and organolithium reagents perform well in the reaction, providing primary sulfonamides in good to excellent yields in a convenient one-step process.

Optimizing thiadiazole analogues of resveratrol versus three chemopreventive targets

Chemoprevention is an approach to decrease cancer morbidity and mortality through inhibition of carcinogenesis and prevention of disease progression. Although the trans stilbene derivative resveratrol has chemopreventive properties, its action is compromised by weak non-specific effects on many biological targets. Replacement of the stilbene ethylenic bridge of resveratrol with a 1,2,4-thiadiazole heterocycle and modification of the substituents on the two aromatic rings afforded potential chemopreventive agents with enhanced potencies and selectivities when evaluated as inhibitors of aromatase and NF-κB and inducers of quinone reductase 1 (QR1).

Sulfinylamine metathesis at oxo metal species--convenient entry into imido metal chemistry

The exchange of terminal metal oxo functionalities by N-organo and N-sulfonylimido functionalities via metathesis with bent, thus very reactive sulfinyl amines R-NSO and sulfinyl sulfonylamides R-SO(2)-NSO is described. It is demonstrated that in many cases sulfinyl amine metathesis offers a more convenient entry into imido complex synthesis than the much better investigated isocyanate metathesis at oxo complexes or condensation reactions with amines and silylated amines. Improved syntheses for some known key compounds and several new complexes of the type [V(NR)Cl(3)] and [M(NR)(2)Cl(2)] (M = Cr, Mo, W) are described. Emphasis is put on the synthesis of formerly unknown base free Lewis acids with electron-withdrawing N-substituents such as haloaryl and sulfonylaryl. Surprisingly, even [CrO(2)Cl(2)] is selectively transformed by sulfinylamines into aryl imido derivatives without any reduction by sulfur dioxide. The molecular structures of novel haloaryl imido complexes [Cr(NAr)(2)Cl(2)] Ar = C(6)F(5) and 2,4,6-Cl(3)C(6)H(2) as determined by X-ray crystallography are reported.