Expanding Radical Chloropentafluorosulfanylation of Alkynes.

The chloropentafluorosulfanylation of alkynes is a delicate but crucial operation for accessing SF5-alkynes that serve as substrates in numerous transformations. Dolbier's procedure using Et3B/O2 was the most efficient approach, while recent efforts make use of other initiators and light activation. We found that THF, as a single stimulus, is sufficient to trigger the reaction of SF5Cl with alkynes. We determined the configuration of Cl/SF5 products and clarified the structure of side-products.

Tracking SF5 I in the Iodopentafluorosulfanylation of Alkynes.

In the vibrant field of SF5 chemistry, SF5 X reagents (X=F, Cl, Br) are at the heart of current investigations in radical pentafluorosulfanylation reactions. SF5 I is the missing link whose existence has not been reported despite its potential as SF5 donor. This study reports the formal addition of the hitherto unknown SF5 I reagent to alkynes by means of a combination of SF5 Cl/KI/18-crown-6 ether. The exclusive regio- and stereoselective synthesis of unprecedented (E)-1-iodo-2-(pentafluoro-λ6 -sulfanyl) alkenes was achieved. A consensus was reached through computational and mechanistic studies for the realistic formation of SF5 - anion but not SF5 I in solution and the rational involvement of SF5 ⋅ and iodine radicals in the iodo pentafluorosulfanylation reaction.

Iridium-Catalyzed Direct Reductive Amination of Ketones and Secondary Amines: Breaking the Aliphatic Wall.

Invited for the cover of this issue are Matthieu Jouffroy from Discovery Process Research at Janssen Pharmaceutica N.V. and the group of Rafael Gramage-Doria at the University of Rennes. The image depicts an Ir-based catalytic system "fueled" by hydrogen for the direct reductive amination of ketones and secondary amines, allowing complex aliphatic tertiary amines to be prepared and, so, new chemical space to be reached. Read the full text of the article at 10.1002/chem.202201078.

Iridium-Catalyzed Direct Reductive Amination of Ketones and Secondary Amines: Breaking the Aliphatic Wall.

Direct reductive amination (DRA) is a ubiquitous reaction in organic chemistry. This transformation between a carbonyl group and an amine is most often achieved by using a super stoichiometric amount of hazardous hydride reagents, thus being incompatible with many sensitive functional groups. DRA could also be achieved by means of chemo- or biocatalysis, thereby attracting the interest of industry as well as academic laboratories due to the virtually perfect atom economy. Although DRAs are well-established for substrate pairs such as aldehydes with either 1° or 2° amines as well as ketones with 1° amines, the current methodologies are limited in the case of ketones with 2° amines. Herein, we present a general DRA protocol that overcomes this major limitation by means of iridium catalysis. The applicability of the methodology is demonstrated by accessing an unprecedented range of biologically relevant tertiary amines starting from both aliphatic ketones and aliphatic amines. The choice of a disphosphane ligand (Josiphos A or Xantphos) is essential for the success of the transformation.

Access to [2,1]Benzothiazine S,S-Dioxides from ß-Substituted o-Nitrostyrenes and Sulfur.

[2,1]Benzothiazine S,S-dioxides 2 were synthesized by simply heating o-nitrostyrenes with elemental sulfur in 3-picoline with complete atom economy. This reaction was found to occur without any added catalyst and consist of a cascade of reduction of the nitro group, sulfuration of a C-H of the double bond, oxidation of a sulfur atom to its highest oxidation state by the migration of two oxygen atoms from the nitro group, and formation of new N-S bonds. Furthermore, the method could also be applied to o-nitrocinnamamides and cinnamate esters.