Novel Alkenylative Cyclization Using a Ruthenium Catalyst

Abstract

Novel alkenylative cyclization of enyne was developed using Cp*RuCl(cod) under ethylene gas at room temperature.

Enyne Metathesis–Oxidation Sequence for the Synthesis of 2‐Phosphono Pyrroles: Proof of the “Yne‐then‐Ene” Pathway

“…To detect this compound, derivative 14 h was dissolved in C 6 D 6 and treated with the first-generation Grubbs catalyst 1 (Scheme 7). The reaction could easily be monitored by using 31 P NMR spectroscopy. The intensity of the signal of 1 (d = 36.9 ppm) slowly decreased and at the same time a new signal appeared at d = 33.7 ppm.…”

“…Synthesis of N-benzyl a-aminoalkenyl phosphonates 11: a-Aminoalkenyl phosphonate 10 (5 mmol), K 2 CO 3 (20 mmol), NaI (0.5 mmol), and acetone (10 mL) were added to a round-bottomed flask. Then, benzyl bromide (10 mmol) was added and the mixture was refluxed for 24 h. The course of the reaction was conveniently monitored by means of 31 P NMR spectroscopic analysis of samples taken directly from the reaction mixture. After complete conversion of the starting material, the solids were removed by filtration and the solvent was removed by evaporation under reduced pressure.…”

“…The solution was refluxed under a nitrogen atmosphere and Grubbs second-generation catalyst 2 (0.02 mmol, 5 mol %) was added to this boiling solution. The reaction mixture was then further refluxed for 16 h. The course of the reaction was conveniently monitored by means of 31 P NMR spectroscopic analyses of samples taken directly from the reaction mixture. The product was coated on silica gel by removal of the solvent in vacuo and purified by flash chromatography.…”

Dialkylzinc‐Mediated Atom Transfer Sequential Radical Addition Cyclization

“…Such transformations have mainly been promoted with transition metals. [13][14][15] To the best of our knowledge, two examples of α-alkylidene-lactone syntheses by radical methodologies from propiolic esters, using tributyltin hydride or perfluoroalkyl iodides, have been reported. [16] One example of formation of α-alkylidene-γ-lactams through the second methodology has been described.…”

Stereoselective Nickel‐Catalyzed [2+2+2] Cycloadditions and Alkenylative Cyclizations of Ene‐Allenes and Alkenes

“…The structure of cis-disubstituted Ntosyl pyrrolidine 19 was confirmed by X-ray crystallography (Figure 1). [11] Interestingly, exchanging P(o-tol) 3 for PBu 3 in the reaction of ene-allene 1 with tert-butyl acrylate led to an alternative catalytic pathway-instead of [2+2+2] cycloaddition [Eq. (6)], the product of an alkenylative carbocyclization formed in high yield as a single diastereomer [Eq.…”