The cross-coupling reaction of arylboronic acid with chloroarenes to give biaryls was carried out in high yields at 70-80 degrees C in the presence of a nickel(0) catalyst and K(3)PO(4) (3 equiv) in dioxane or benzene. The nickel(0) catalyst in situ prepared from NiCl(2).L (L = dppf, 2PPh(3)) (3-10 mol %) and 4 equiv of BuLi at room temperature was recognized to be most effective. The reaction can be applicable to a wide range of chloroarenes having an electron-withdrawing or an electron-donating group such as 4-NC, 4-CHO, 2- or 4-CO(2)Me, 4-COMe, 4-NHAc, 4-Me, 4-OMe, 4-NH(2), and 4-NMe(2). The Hammett's plot of the substituent effect of chloroarenes revealed that the reaction involves a rate-determining oxidative addition of chloroarenes to the nickel(0) complex.

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We report the synthesis and photophysical/photoredox characteristics of a novel tricarbonyl rhenium(I) complex having a (dimesityl)boryldurylethynyl (DBDE) group at the 4-position of a 1,10-phenanthroline (phen) ligand, [Re(CO)(3)(4-DBDE-phen)Br] (ReB). ReB in tetrahydrofuran at 298 K showed the metal-to-ligand charge transfer (MLCT) emission at around 681 nm with the lifetime (τ(em)) of 900 ns. The relatively long emission lifetime of ReB compared with that of [Re(CO)(3)(phen)Br] (RePhen, τ(em) = 390 ns) was discussed on the basis of the temperature dependent τ(em) and Franck-Condon analysis of the emission spectra of the two complexes. Emission quenching studies of both ReB and RePhen by a series of electron donors revealed that the photoinduced electron transfer (PET) quenching rate constant of ReB was faster than that of RePhen at a given Gibbs free energy change of the PET reaction (ΔG(ET)(0) > -0.5 eV). All of the results on ReB were discussed in terms of the contribution of the CT interaction between the π-orbital(s) of the aryl group(s) and the vacant p-orbital on the boron atom in DBDE to the MLCT state of the complex.

The chiral indole is an important structure in organic chemistry. We have developed an enantioselective hydrogen transfer reaction of indolylmethanol, which is characterized by the combined use of benzothiazoline and a newly synthesized chiral phosphoric acid. The reaction furnished indoles bearing a chiral tertiary carbon center at the 3-position in high to excellent yields and with excellent enantioselectivities, most of which are greater than 95% ee. The chiral indole was converted into an inhibitor of leukotriene production while retaining excellent ee.

Fluorous solid‐phase extraction (FSPE) is a useful technique for efficient selective enrichment of fluorous compounds from nonfluorous molecules. Sphingolipids and their metabolites, which are ubiquitous building blocks of eukaryotic and prokaryotic cell membranes, play crucial roles, for example, as signaling molecules. However, details of the functions and metabolic mechanisms of exogenous sphingolipids have remained unknown compared with those of their endogenous analogs. To better understand these unknown roles, chemical probes with appropriate biological and physicochemical properties are needed. In this study, we designed and synthesized new fluorous sphingolipids to reveal these roles. Furthermore, we confirmed that they could be efficiently and rapidly separated from normal sphingolipids by FSPE, and that they hardly showed any cytotoxic activity, similarly to normal sphingolipids at the same dose. We also showed that these fluorinated ceramides could act as metabolic substrates for sphingomyelin synthase 2 (SMS2). This demonstrates their potential for further biological studies.