Elsevier Science SA. Acta Medica Okayama 0022-328X 696 1 2011 Rhenium-catalyzed insertion of terminal alkenes into a C(sp(2))–H bond and successive transfer hydrogenation 348 351 EN Yoichiro Kuninobu Takahiro Nakahara Peng Yu Kazuhiko Takai Treatment of aromatic aldimines with terminal alkenes in the presence of a rhenium catalyst, [HRe(CO)(4)](n), gives 2-alkenylbenzylamines in good to excellent yields. This reaction proceeds via the insertion of the alkene into a C-H bond at the ortho-position of the imino group of the aromatic aldimine followed by sequential beta-hydride elimination from the formed alkyl rhenium intermediate and then by hydrogenation of the imino group of the aldimine. No potential conflict of interest relevant to this article was reported.

Elsevier Science SA. Acta Medica Okayama 1011-1344 104 1-2 2011 Structure of the catalytic, inorganic core of oxygen-evolving photosystem II at 1.9 Å resolution 9 18 EN Keisuke Kawakami Yasufumi Umena Nobuo Kamiya Jian-Ren Shen The catalytic center for photosynthetic water-splitting consists of 4 Mn atoms and 1 Ca atom and is located near the lumenal surface of photosystem II. So far the structure of the Mn(4)Ca-cluster has been studied by a variety of techniques including X-ray spectroscopy and diffraction, and various structural models have been proposed. However, its exact structure is still unknown due to the limited resolution of crystal structures of PSII achieved so far, as well as possible radiation damages that might have occurred. Very recently, we have succeeded in solving the structure of photosystem II at 1.9 angstrom. which yielded a detailed picture of the Mn(4)CaO(5)-cluster for the first time. In the high resolution structure, the Mn(4)CaO(5)-cluster is arranged in a distorted chair form, with a cubane-like structure formed by 3 Mn and 1 Ca, 4 oxygen atoms as the distorted base of the chair, and 1 Mn and 1 oxygen atom outside of the cubane as the back of the chair. In addition, four water molecules were associated with the cluster, among which, two are associated with the terminal Mn atom and two are associated with the Ca atom. Some of these water molecules may therefore serve as the substrates for water-splitting. The high resolution structure of the catalytic center provided a solid basis for elucidation of the mechanism of photosynthetic water splitting. We review here the structural features of the Mn(4)CaO(5)-cluster analyzed at 1.9 angstrom resolution, and compare them with the structures reported previously. No potential conflict of interest relevant to this article was reported.