Ruthenium-Catalyzed Cycloisomerization of 2‑Alkynylanilides: Synthesis of 3‑Substituted Indoles by 1,2-Carbon Migration

We developed ruthenium-catalyzed cycloisomerization of alkynylanilides that gave 3-substituted indoles in high yields. The reaction proceeded via the disubstituted vinylidene ruthenium complex that was formed by the 1,2-carbon migration

(<i>Z</i>)‑Selective Hydrosilylation of Terminal Alkynes with HSiMe(OSiMe₃)₂ Catalyzed by a Ruthenium Complex Containing an N‑Heterocyclic Carbene

The N-heterocyclic-carbene-ligated ruthenium complex [RuHCl­(CO)­(H₂IMes)­(PCy₃)] exhibits high catalytic activity for the (<i>Z</i>)-selective hydrosilylation of various terminal alkynes with 1,1,1,3,5,5,5-heptamethyl­trisiloxane (HSiMe­(OSiMe₃)₂). The stereoretentive derivatization of the (<i>Z</i>)-alkenylsiloxanes allows the synthesis of biologically active compounds, e.g. potent antitumor agents and inhibitors for induced-NO synthase

Synthesis of Tricyclic Benzazocines by Aza-Prins Reaction

The aza-Prins reaction of 3-vinyl­tetra­hydro­quinolines with aldehydes proceeded smoothly in the presence of hydrogen halides, and the tricyclic benzazocine derivatives were isolated in good to high yields. The reaction would proceed through the formation and cyclization of the iminium ion intermediate

Synthesis of Tricyclic Benzazocines by Aza-Prins Reaction

The aza-Prins reaction of 3-vinyl­tetra­hydro­quinolines with aldehydes proceeded smoothly in the presence of hydrogen halides, and the tricyclic benzazocine derivatives were isolated in good to high yields. The reaction would proceed through the formation and cyclization of the iminium ion intermediate

Synthesis of Tricyclic Benzazocines by Aza-Prins Reaction

The aza-Prins reaction of 3-vinyl­tetra­hydro­quinolines with aldehydes proceeded smoothly in the presence of hydrogen halides, and the tricyclic benzazocine derivatives were isolated in good to high yields. The reaction would proceed through the formation and cyclization of the iminium ion intermediate

Sequence-Selective Synthesis of Rotacatenane Isomers

Rotacatenane is an interlocked compound composed of two mechanically interlocked macrocyclic components, i.e., a [2]­catenane, and one axle component. In this paper we describe the selective synthesis of isomeric rotacatenanes. Two [2]­rotaxanes with different phenanthroline moieties were synthesized by the oxidative coupling of an alkyne with a bulky blocking group, which proceeded in the cavity of the macrocyclic phenanthroline–Cu complex. The metal template method was used to install another cyclic component: the tetrahedral Cu­(I) complex, which was composed of a [2]­rotaxane and an acyclic phenanthroline derivative, was synthesized, and the cyclization of the phenanthroline derivative gave the rotacatenane. The sequential isomers of rotacatenanes were distinguished by ¹H and ¹³C NMR spectroscopy

Sequence-Selective Synthesis of Rotacatenane Isomers

Rotacatenane is an interlocked compound composed of two mechanically interlocked macrocyclic components, i.e., a [2]­catenane, and one axle component. In this paper we describe the selective synthesis of isomeric rotacatenanes. Two [2]­rotaxanes with different phenanthroline moieties were synthesized by the oxidative coupling of an alkyne with a bulky blocking group, which proceeded in the cavity of the macrocyclic phenanthroline–Cu complex. The metal template method was used to install another cyclic component: the tetrahedral Cu­(I) complex, which was composed of a [2]­rotaxane and an acyclic phenanthroline derivative, was synthesized, and the cyclization of the phenanthroline derivative gave the rotacatenane. The sequential isomers of rotacatenanes were distinguished by ¹H and ¹³C NMR spectroscopy

Synthesis of Mechanically Planar Chiral <i>rac-</i>[2]Rotaxanes by Partitioning of an Achiral [2]Rotaxane: Stereoinversion Induced by Shuttling

Mechanically planar chiral [2]­rotaxanes were synthesized by the introduction of bulky pyrrole moieties into the axle component of an achiral [2]­rotaxane. The enantiomers were separated by chiral HPLC. The shuttling of the ring component between the two compartments at high temperature induced the stereoinversion of the mechanically planar chiral [2]­rotaxane. The rate of the stereoinversion was studied quantitatively, and the kinetic parameters were determined

Mechanistic Origin of Chemo- and Regioselectivity of Nickel-Catalyzed [3 + 2 + 2] Cyclization Reaction

A density functional theory (DFT) study was performed to elucidate the mechanism of the Ni-catalyzed [3 + 2 + 2] cyclization reaction of cyclopropylideneacetate with two alkynes. A systematic search showed that the nature of the alkynes determines the choice between two reaction pathways and hence the regioselectivity. Strongly electron-deficient acetylenes preferentially afford 2,5-disubstituted products via nickelacyclopentadienes generated by [2 + 2] cocyclization, whereas normal alkynes afford 3,4- or 3,5-products via an unprecedented pathway involving a [3 + 2] nickelacycle intermediate

Synthesis of Rhodium–Primary Thioamide Complexes and Their Desulfurization Leading to Rhodium Sulfido Cubane-Type Clusters and Nitriles

Although molecular thioamide complexes of late-transition metals have been prepared since 1979, the chemistry of primary thioamide complexes remains relatively unexplored. To shed light on this area, we have investigated synthesis, structures, and reactivities of simple rhodium organometallic complexes with a primary arenecarbothioamide ligand [Cp*RhCl₂{SC­(Ar)­NH₂-κ¹<i>S</i>}] (Cp* = η⁵-C₅Me₅). Intra- and intermolecular hydrogen bonding in the thioamide complexes is discussed on the basis of ¹H NMR spectroscopy and X-ray analysis. When these rhodium complexes were treated with a large excess amount of Et₃N, desulfurization of the thioamide ligand took place to give arenecarbonitriles (ArCN) in high GC yield and the cubane-type cluster [(Cp*Rh)₄(μ₃-S)₄] (<b>3</b>) in good yield as the organometallic product. Use of a smaller amount (2.4 equiv) of Et₃N followed by treatment with NaBAr^F₄ (Ar^F = 3,5-(CF₃)₂C₆H₃) led to the isolation of the cationic clusters [(Cp*Rh)₄(μ₃-S)₄]­(BAr^F₄) or [(Cp*Rh)₄(μ₃-S)₄]­(BAr^F₄)₂ in low yield. Reaction mechanisms of the desulfurization of the coordinated thioamides and the formation and one- or two-electron oxidation of <b>3</b> during the desulfurization are discussed