Selective S-Arylation of Sulfenamides with Arynes: Access to Sulfilimines

Synthesis of Sulfilimines via Visible-Light-Mediated Triplet Energy Transfer to Sulfonyl Azides

Sulfilimines and their derivatives have garnered considerable interest in both synthetic and medicinal chemistry. Photochemical nitrene transfer to sulfides is known as a conventional synthetic approach to sulfilimines. However, the existing methods have a limited substrate scope stemming from the incompatibility of singlet nitrene intermediates with nucleophilic functional groups. Herein, we report the synthesis of N-sulfonyl sulfilimines via visible-light-mediated energy transfer to sulfonyl azides, uncovering the previously overlooked reactivity of triplet nitrenes with sulfides. This reaction features broad functional group tolerance, water compatibility, and amenability to the late-stage functionalization of drugs. Thus, this work represents an important example of energy transfer chemistry that overcomes challenges in traditional synthetic methods.

1,2-Difunctionalization of Aryne with Sulfenamide and Organohalide: Mild and Metal-Free Access to S-(o-Halo)aryl Sulfilimine

A mild and metal-free approach has been developed for 1,2-difunctionalization of aryne using sulfenamides as a nucleophile and a halogen source (CX4) as an electrophile to synthesize S-(o-halo)aryl sulfilimines. The late-stage functionalizations of halide handles via Suzuki-Miyaura and Buchwald-Hartwig reactions exhibit the synthetic utilities of the products. The chemoselectivity, regioselectivity, rapidity, and use of economical CCl4 are the advantages of this protocol.

Synthesis of N-Acylsulfenamides from (Hetero)Aryl Iodides and Boronic Acids by One-Pot Sulfur-Arylation and Dealkylation

A general one-pot approach to diverse N-acylsulfenamides from a common S-phenethylsulfenamide starting material is reported. This approach was demonstrated by C-S bond formation utilizing commercially abundant (hetero)aryl iodides and boronic acids to provide sulfilimine intermediates that undergo thermal elimination of styrene. In contrast, all prior approaches to N-acylsulfenamides rely on thiol inputs to introduce sulfenamide S-substituents. A broad scope of reaction inputs was demonstrated including for approved drugs and drug precursors with dense display of functionality. Several different types of sulfur functionalization were performed on a sulfenamide derived from a complex precursor of the blockbuster anticoagulant drug apixaban, highlighting the utility of this approach for the introduction of high oxidation state sulfur groups in complex bioactive compounds. Mechanistic studies established that the key styrene elimination step proceeds by a concerted elimination that does not require reagents or catalysts, and therefore, this one-pot approach should be applicable to the synthesis of N-acylsulfenamides utilizing diverse electrophiles and reaction conditions for C-S bond formation.

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.