Iron-catalyzed cross-coupling of alkenyl sulfides with Grignard reagents

[reaction: see text] The iron-catalyzed cross-coupling reaction of alkenyl sulfides with Grignard reagents is described. While the cross-coupling proceeds efficiently at alkenyl-S bonds, almost no cross-coupling takes place at aryl-S bonds, attesting to a unique selectivity of iron catalysis. The beneficial effect of potentially coordinating 2-pyrimidyl group on sulfur is also described.     

Construction of Pt complex within Zr-based MOF and its application for hydrogen production under visible-light irradiation

The present article deals with Pt complex construction within Zr-based MOF having bipyridine units in the framework (Zr-MOF-bpy-PtCl₂) and its photocatalytic activity for hydrogen production under visible-light irradiation (λ > 420 nm). Zr-MOF-bpy-PtCl₂ is prepared by the construction of a Zr-based MOF using 2,2′-bipyridine-5,5′-dicarboxylic acid (Zr-MOF-bpy), and subsequent complexation reaction with K₂PtCl₄. XRD and N₂ adsorption–desorption measurements have revealed that both Zr-MOF-bpy and Zr-MOF-bpy-PtCl₂ have a UiO-type structure. From the results of UV–Vis and XAFS measurements, the incorporated Pt species has been proven to be in square planar geometry involving two N atoms and two Cl atoms as a result of the Pt coordination with bipyridine units in the framework. Zr-MOF-bpy-PtCl₂ has been employed for a hydrogen production reaction from water containing a sacrificial electron donor under visible-light irradiation (λ > 420 nm). Zr-MOF-bpy-PtCl₂ realizes steady hydrogen production, and the amount of evolved hydrogen reaches 8.3 μmol after the 9 h reaction period, while Zr-MOF-bpy exhibits no photocatalytic activity under the same conditions. It has also been found that the activity of Zr-MOF-bpy-PtCl₂ is superior to that of the corresponding homogeneous complex analogue (bpy)PtCl₂.     

Generation of 2-Carboethoxyethylzinc iodide and 3-carboethoxypropylzinc iodide and their application to the synthesis of γ- and δ-keto esters

2-Carboethoxyethylzinc iodide and 3-carboethoxypropylzinc iodide are generated by the reaction of the corresponding iodoesters with Zn-Cu couple and utilized for the palladium catalyzed coupling reaction with acid chloride to quantitatively provide gamma- and delta- keto esters, respectively.     

Ultrafast fluorescence detection in tris(2,2'-bipyridine)ruthenium(II) complex in solution: relaxation dynamics involving higher excited states

The excited-state dynamics of a transition metal complex, tris(2,2'-bipyridine)ruthenium(II), [Ru(bpy)(3)](2+), has been investigated using femtosecond fluorescence upconversion spectroscopy. The relaxation dynamics in these molecules is of great importance in understanding the various ultrafast processes related to interfacial electron transfer, especially in semiconductor nanoparticles. Despite several experimental and theoretical efforts, direct observation of a Franck-Condon singlet excited state in this molecule was missing. In this study, emission from the Franck-Condon excited singlet state of [Ru(bpy)(3)](2+) has been observed for the first time, and its lifetime has been estimated to be 40 +/- 15 fs. Biexponential decays with a fast rise component observed at longer wavelengths indicated the existence of more than one emitting state in the system. From a detailed data analysis, it has been proposed that, on excitation at 410 nm, crossover from higher excited (1)(MLCT) states to the vibrationally hot triplet manifold occurs with an intersystem crossing time constant of 40 +/- 15 fs. Mixing of the higher levels in the triplet state with the singlet state due to strong spin-orbit coupling is proposed. This enhances the radiative rate constant, k(r), of the vibrationally hot states within the triplet manifold, facilitating the upconversion of the emitted photons. The vibrationally excited triplet, which is emissive, undergoes vibrational cooling with a decay time in the range of 0.56-1.3 ps and relaxes to the long-lived triplet state. The results on the relaxation dynamics of the higher excited states in [Ru(bpy)(3)](2+) are valuable in explaining the role of nonequilibrated higher excited sensitizer states of transition metal complexes in the electron injection and other ultrafast processes.     

Schmitt-Vogel type lemma for reductions

The lemma given by Schmitt and Vogel is an important tool in the study of the arithmetical rank of squarefree monomial ideals. In this paper, we give a Schmitt-Vogel type lemma for reductions as an analogous result.     

Functionalization of a Single C−F Bond of Trifluoromethylarenes Assisted by an ortho-Silyl Group Using a Trityl-Based All-in-One Reagent with Ytterbium Triflate Catalyst

Catalytic thiolation and azidation of a single C−F bond of trifluoromethylarenes were achieved assisted by an ortho-silyl group with all-in-one reagents to generate a trityl cation and nucleophiles. The reactions catalyzed by ytterbium triflate efficiently afforded a wide variety of difluoromethylenes avoiding the further C−F bond cleavage, by virtue of the mild conditions without the generation of a Brønsted acid.     

Aerobic Dehydrogenation of N-Heterocycles with Grubbs Catalyst: Its Application to Assisted-Tandem Catalysis to Construct N-Containing Fused Heteroarenes

An aerobic dehydrogenation of nitrogen-containing heterocycles catalyzed by Grubbs catalyst is developed. The reaction is applicable to various nitrogen-containing heterocycles. The exceptionally high functional group compatibility of this method was confirmed by the oxidation of an unprotected dihydroindolactam V to indolactam V. Furthermore, by taking advantage of the oxygen-mediated structural change of the Grubbs catalyst, we integrated ring-closing metathesis and subsequent aerobic dehydrogenation to develop the novel assisted-tandem catalysis using molecular oxygen as a chemical trigger. The utility of the assisted-tandem catalysis was demonstrated by the concise synthesis of N-containing fused heteroarenes including a natural antibiotic, pyocyanine.