Experimental and Computational Studies of the Iron‐Catalyzed Selective and Controllable Defluorosilylation of Unactivated Aliphatic gem‐Difluoroalkenes

Abstract

The first iron-catalyzed defluorosilylation of unactivated gem-difluoroalkenes was developed, delivering gemdisilylated alkenes and (E)-silylated alkenes with excellent efficiency.T his protocol features good functional group compatibility and excellent regio-and stereoselectivity,e nabling the late-stage silylation of biologically relevant compounds,t hus providing good opportunities for applications in medicinal chemistry.Preliminary mechanistic studies and DFT calculations reveal that anucleophilic addition and elimination of the second C À Fb ond might be involved in the disilylation catalytic system, demonstrating unusual reactivity characteristics of iron catalysis.Scheme 1. The methods for the synthesis of gem-disilylated alkenes.

Iron-Catalyzed Ligand-Controlled Silylation or Borylation of Ni-triles with Bpin-SiEt3 via C-CN Bond Cleavage

“…The mechanism of iron-catalyzed silylation reaction was depicted in Scheme 3. First, the iron species was treated with silylborane reagent 2a to form an iron-boryl or iron-silyl complex I, [54][55] which was then coordinated with the nitrile to afford complex II, followed by borane insertion to form iron species III. Intermediate iron complex III then delivered iron-aryl complex IV, which reacted with silylborane reagent 2a to afford the silylated product or borylated product and regenerated iron-boryl or iron-silyl complex I.…”

“…Our recent studies revealed that iron catalysts could react with silylborane and borane reagents to generate iron-silyl and iron-boryl species, which could then promote the silylation and borylation of C-F bonds. [54][55] Inspired by these findings, [51][52][53][54][55] we envisioned that the bifunctional silylborane reagents could serve as both silicon and borane reagents in the iron catalytic system, and undergo the silylation and borylation with the aid of ligands, providing the corresponding silylated and borylated products, respectively (Scheme 1c). Herein, we report the first example of selective decyanative silylation or borylation of the same substrate using a common silylborane as either the silicon or borane reagent under iron catalysis.…”

On the application of 3d metals for C–H activation toward bioactive compounds: The key step for the synthesis of silver bullets

“…Therefore, it has been and still is widely used in many fields, from ancient but still applicable appliance as feedstock to construct basic steel tools [148], to the most recent nanotechnology field [149]. Iron presents powerful catalyst properties [150][151][152], including applications in C-H activation reactions [153][154][155].…”

“…The distinction of which reaction takes place relies not only on the structure of the coupling partner, but also on the structure of the reactant itself since there are two removable hydrogen atoms necessary for the tetrasubstituted alkene to be formed (Scheme 71A and B). The method was also applied in a late-stage functionalization of bioactive molecules such as an estrone derivative (229) and donepezil (152) [219]. In both cases, the final products were successfully formed in good yields (Scheme 71C).…”

Iron-Catalyzed Diborylation of Unactivated Aliphatic gem-Dihalogenoalkenes: Synthesis of 1,2-Bis(boryl)alkanes

“…Usually, many unpredictable reactions are discovered by the one-electron transfer pathway, thus highlighting the superiority of iron catalysis . In our previous work, we found different reactivities of iron catalysis. Fortunately, in the recent defluorosilylation of unactivated aliphatic gem -difluoroalkenes, iron catalysis showed different reactivity from copper, palladium, and nickel.…”