Ligand-Controlled Regiodivergent Nickel-Catalyzed Hydrocyanation of Silyl-Substituted 1,3-Diynes

Abstract

A regiodivergent nickel-catalyzed hydrocyanation of 1-aryl-4-silyl-1,3-diynes is reported. When appropriate bisphosphine and phosphine–phosphite ligands are applied, the same starting materials can be converted into two different enynyl nitriles with good yields and high regioselectivities. The DFT calculations unveiled that the structural features of different ligands bring divergent alkyne insertion modes, which in turn lead to different regioselectivities. Moreover, the synthetic value of the cyano-containing 1,3-enynes has been demonstrated with several downstream transformations.

Catalytic Hydrofunctionalization Reactions of 1,3-Diynes

“…In sharp contrast to simple alkynes, hydrocyanation of 1,3-diynes remains a neglected area of research. Indeed, just one very recent work can be found in the literature describing the Ni-catalyzed regio-divergent hydrocyanation of unsymmetrical 1-aryl-4-silyl-1,3-butadiynes (Scheme 20) [44]. The reactions, performed in toluene with catalytic amounts of [Ni(COD) 2 ] (COD = 1,5-cyclooctadiene) and acetone cyanohydrin as the HCN surrogate, afforded with high regioselectivity and complete stereoselectivity (syn addition) two kinds of enynyl nitriles, i.e., compounds 34 and 35, depending on the conditions and, capitally, the ligand employed.…”

Palladium(II)-Catalyzed Intramolecular [2 + 2 + 2] Annulation of Indolyl 1,3-Diynes: Construction of Azepino-Fused Carbazoles

“…As a result of the unique two conjugated C≡C bonds, they could serve as either 2C or 4C synthons in synthetic organic chemistry and have been found in many successful applications in chemical, pharmaceutical, and material sciences. Among most of the reported cases, 1,3-diynes serve as precursors for intermolecular addition reactions, affording functionalized conjugated enynes or 1,3-dienes via transition-metal-catalyzed hydrogenation, hydrosilylation, hydrothiolation, hydrocyanation, hydroarylation, hydroborylation, hydroamination, hydroamidation, , and carbonylation (Figure a). For instance, the seminal works were reported by Beller and co-workers recently, in which they developed three elegant methods for highly selective dicarbonylation, monocarbonylation, and monohydroamidation of 1,3-diynes.…”

Enantioselective Nickel-Catalyzed Hydrocyanative Desymmetrization of Norbornene Derivatives

“…L3 could afford 3a with good enantioselectivity albeit with low yield (Table , entry 3). In addition, our previous reports suggested that the dihedral angle of diphosphine ligand exhibited dominance over the control of selectivity of hydrocyanation. These promising results encouraged us to evaluate the other axially chiral diphosphine ligands.…”