Structural features and reactivity of (sparteine)PdCl_2: a model for selectivity in the oxidative kinetic resolution of secondary alcohols

The chiral ligand (−)-sparteine and PdCl_2 catalyze the enantioselective oxidation of secondary alcohols to ketones and thus effect a kinetic resolution. The structural features of sparteine that led to the selectivity observed in the reaction were not clear. Substitution experiments with pyridine derivatives and structural studies of the complexes generated were carried out on (sparteine)PdCl2 and indicated that the C1 symmetry of (−)-sparteine is essential to the location of substitution at the metal center. Palladium alkoxides were synthesized from secondary alcohols that are relevant steric models for the kinetic resolution. The solid-state structures of the alkoxides also confirmed the results from the pyridine derivative substitution studies. A model for enantioinduction was developed with C1 symmetry and Cl− as key features. Further studies of the diastereomers of (−)-sparteine, (−)-α-iso- and (+)-β-isosparteine, in the kinetic resolution showed that these C_2-symmetric counterparts are inferior ligands in this stereoablative reactio

An Experimentally Derived Model for Stereoselectivity in the Aerobic Oxidative Kinetic Resolution of Secondary Alcohols by (Sparteine)PdCl_2

A model for asymmetric induction in palladium-catalyzed aerobic oxidative kinetic resolution is described. The model is based on coordination complexes and general reactivity trends of the parent (sp)PdCl2 catalyst. The first example of a nonracemic chiral palladium alkoxide complex is presented, and exhibits the subtle steric influences of the C1symmetric ligand sparteine

Daftar Isi

Daftar Isi MediaTrend Vol. XI No. 2 Oktober 201

Wighton: the church, the village and its people, 1400-1500

When, how, by whom and in what circumstances were Norfolk’s medieval churches rebuilt in the long fifteenth century? Despite the importance of this extraordinary and historic burst of architectural creativity, the answers to these key questions have long proved elusive. A perceived lack of archaeological and documentary evidence has left historians largely in the dark. This thesis addresses the gap in our knowledge by focusing on a single church and village - All Saints in Wighton, near the north coast of the county. The choice of such an apparently narrow subject has allowed a sustained and intense focus on both the fabric of the building and the scattered, partial evidence which survives in the archives. And while the focus has been narrow, the approach taken has been broad and creative. It has included an analysis of masons’ marks, the counting of arch voussoirs, an unusually wide, eclectic and exhaustive collation and investigation of surviving documents, together with detailed comparisons with other churches in the vicinity. As such it aims to offer a new model for architectural and social historical research and - hopefully - it will be regarded as a success. The research has identified a reliable chronology for the nave and chancel of All Saints, estimated the cost of its construction and established the most likely model of fundraising needed to raise that money. It has reconstructed the village economy and its community in some detail and identified and profiled the individuals who were most likely to have paid for the project. Lastly, as a consequence of its investigations, it has proposed significant revisions in the date of important stained glass at All Saints and several other Norfolk churches

Fostering Progress in Children's Developing Geoscience Interests

Interest is a complex construct, yet is often treated by researchers and other authors as being a non-problematic uni-faceted concept. Negligible research has been undertaken into the geoscience interests of teachers and students, with even less probing of interrelationships between individual, situational and topic interest. Interest research is very weakly-developed in the UK, with many recent publications emanating from several pivotal countries including Canada, Germany, Australia and the USA. In recent years the interest research community has been developing theory, including a four-phase model which provides a framework for analysing the progressive development of learners' interest from "triggered situational interest" to "well-developed individual interest" (Hidi and Renninger, 2006). In order to identify teachers' possible instructional starting points, a questionnaire survey of 652 children aged 11 and 12 years was undertaken to investigate the nature of their individual geoscience interests. Selected data from a second study of 51 serving teachers were also used to compare the geoscience interests of teachers and children and to compare those interests with actual classroom experiences of selected geoscience concepts. Several mismatches between teachers' and children's interests were identified, alongside further mismatches between interest and classroom geoscience experiences. In order to illustrate children's growth towards a 'well-developed individual geoscience interest', comprising both cognitive and affective elements, the four-phase model of interest development was examined in the context of the planning of geoscience learning activities. The implications of this model for geoscience education are examined in relation to the empirical results reported here and in the two previous related papers

Evasion of the toxic effects of oxygen

Oxygen is an efficient terminal electron acceptor in respiratory pathways. During aerobic respiration the electron transport chain generates free radical oxygen species as a result of electron leakage; this generation of toxic species is proportional to the oxygen tension (51). In addition, toxic oxygen species (TOS) may be formed exogenously, for example, by chemical processes or through radiation. TOS also result from the oxidative burst of polymorphonuclear leukocytes (PMN). Infection with Helicobacter pylori induces an inflammatory response (gastritis), which leads to an increase in the level of TOS in the gastric mucosa and the gastric juice (4, 24–26, 59). This increase in the level of toxic metabolites is probably the result of the generation of the superoxide anion (O2·− ), a reactive TOS, formed as part of the oxidative burst of PMN and enzymic activities of gastric epithelial cells. There is evidence that H. pylori infection leads to increased production of O2·− via NADPH oxidase in gastric cells, stimulated by lipopolysaccharide as well as xanthine oxidase, another mechanism for the generation of oxygen-derived free radicals (8, 80). In response to increased superoxide anion production in gastric tissue, changes have been detected in the level of expression of human superoxide dismutase (SOD) (12). Human gastric SOD exists as a cytoplasmic copper-zinc-superoxide dismutase (Cu, Zn-SOD) found in gland cells of the gastric body and antral mucosa, and as a manganese-superoxide dismutase (Mn-SOD) within mitochondria (63). An increase in the amount and activity of Mn-SOD has been observed in response to H. pylori infection and gastritis, whereas the amount and activity of the Cu, Zn-SOD remained constant or decreased slightly (39). It has been suggested that the induction of Mn-SOD is in response to increased cytokine production within the inflamed gastric mucosa (39). This situation is reversed following successful treatment of the infection (38). The data suggest that within the gastric environment H. pylori may be exposed to increased levels of TOS. In such an environment it is important for bacterial survival that the impact of such TOS be neutralized

円安トレンドとその背景

はじめに 1.第2次安倍政権と円安 2.市場介入と外貨準備の増減 3.政府短期証券の発行と政府の為替安定化策 4.ゆうちょ銀行・かんぽの資産運用と民間金融機関の動向 むすびにかえて研究ノー