Author
Shinya Kohra
Bio: Shinya Kohra is an academic researcher from Nagasaki University. The author has contributed to research in topics: Methylene & Cycloaddition. The author has an hindex of 19, co-authored 107 publications receiving 1259 citations.
Topics: Methylene, Cycloaddition, Organosilicon, Ketene, Fluoride
Papers published on a yearly basis
Papers
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TL;DR: It is indicated that AdP and DHMS should be considered as candidate estrogenic compounds with the potential to induce hepatic estrogen-responsive genes in male medaka and that these genes may be useful molecular biomarkers for screening estrogenic endocrine-disrupting chemicals in the shortest possible time.
126 citations
TL;DR: It is suggested that MBP has high toxicity for early life stages of the medaka, and that the estrogenic activity of MBP was about 250-fold higher than that of BPA to male medaka.
68 citations
TL;DR: Pentacoordinate triethylammonium bis(catecholato)allylsiliconates were synthesized by reaction of allyltrialkoxysilanes, catechol, and triethyamine as discussed by the authors.
Abstract: Pentacoordinate triethylammonium bis(catecholato)allylsiliconates were synthesized by reaction of allyltrialkoxysilanes, catechol, and triethylamine. The allylsiliconates react with aldehydes without catalyst to give the corresponding homoallyl alcohols in high yields in a completely regiospecific and highly diastereoselective mode. The stereochemistry of the products can be reasonably interpreted by assuming a cyclic six-membered ring transition state. This allylation of aldehydes can also be effected by mixing them with an allyltrialkoxysilane, an alcool, and an amine, and an amine, generating the allylsiliconate in situ
61 citations
TL;DR: In this paper, nine different food cans, packed with water, were heat-treated for 30 min at 80 or 100°C in order to elucidate the trends associated with the leaching of bisphenol A (BPA) from internal coatings.
Abstract: Nine different food cans, packed with water, were heat-treated for 30 min at 80 or 100°C in order to elucidate the trends associated with the leaching of bisphenol A (BPA) from internal coatings. Low levels of BPA were detected in water from all unheated cans, rising to 0.06 to 32 ng/cm2 after heating at 100°C. Reducing the heat-treatment temperature to 80°C was found to reduce the BPA concentration in the contained water by up to two-thirds. The cans that recorded the highest BPA concentrations in water after heating were found to have components (lid, bottom or body) with high available BPA contents.
61 citations
TL;DR: Polarized ethylenes having both electron-donating (an amino or a methylthio group) and electron-accepting (cyano, carbamoyl, methyl ester) groups on the adjacent two olefinic carbon atoms were prepared by the condensation of S-alkylthioamidinium salts or methyl dithiocarboxylates with the corresponding active methylene compounds in good yields.
59 citations
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TL;DR: A number of improvements have developed the former process into an industrially very useful and attractive method for the construction of aryl -aryl bonds, but the need still exists for more efficient routes whereby the same outcome is accomplished, but with reduced waste and in fewer steps.
Abstract: The biaryl structural motif is a predominant feature in many pharmaceutically relevant and biologically active compounds. As a result, for over a century 1 organic chemists have sought to develop new and more efficient aryl -aryl bond-forming methods. Although there exist a variety of routes for the construction of aryl -aryl bonds, arguably the most common method is through the use of transition-metalmediated reactions. 2-4 While earlier reports focused on the use of stoichiometric quantities of a transition metal to carry out the desired transformation, modern methods of transitionmetal-catalyzed aryl -aryl coupling have focused on the development of high-yielding reactions achieved with excellent selectivity and high functional group tolerance under mild reaction conditions. Typically, these reactions involve either the coupling of an aryl halide or pseudohalide with an organometallic reagent (Scheme 1), or the homocoupling of two aryl halides or two organometallic reagents. Although a number of improvements have developed the former process into an industrially very useful and attractive method for the construction of aryl -aryl bonds, the need still exists for more efficient routes whereby the same outcome is accomplished, but with reduced waste and in fewer steps. In particular, the obligation to use coupling partners that are both activated is wasteful since it necessitates the installation and then subsequent disposal of stoichiometric activating agents. Furthermore, preparation of preactivated aryl substrates often requires several steps, which in itself can be a time-consuming and economically inefficient process.
3,204 citations
TL;DR: The reported levels of BPA in human fluids are higher than the BPA concentrations reported to stimulate molecular endpoints in vitro and appear to be within an order of magnitude of the levels needed to induce effects in animal models.
2,391 citations
TL;DR: Hydroamination of Alkenes and Alkynes under Microwave Irradiation and Nitromercuration Reactions 3878 9.8.4.5.
Abstract: 8.4.5. Nitromercuration Reactions 3878 9. Hydroamination of Alkenes and Alkynes under Microwave Irradiation 3878 * To whom correspondence should be addressed. Phone: +49 241 8
1,685 citations
TL;DR: The growing human literature correlating environmental BPA exposure to adverse effects in humans, along with laboratory studies in many species including primates, provides increasing support that environmental B PA exposure can be harmful to humans, especially in regards to behavioral and other effects in children.
1,438 citations
TL;DR: It has become increasingly apparent that the behavior of Lewis bases as agents for promoting chemical reactions is not merely as an electronic complement of the cognate Lewis acids: in fact Lewis bases are capable of enhancing both the electrophilic and nucleophilic character of molecules to which they are bound.
Abstract: The legacy of Gilbert Newton Lewis (1875-1946) pervades the lexicon of chemical bonding and reactivity. The power of his concept of donor-acceptor bonding is evident in the eponymous foundations of electron-pair acceptors (Lewis acids) and donors (Lewis bases). Lewis recognized that acids are not restricted to those substances that contain hydrogen (Bronsted acids), and helped overthrow the "modern cult of the proton". His discovery ushered in the use of Lewis acids as reagents and catalysts for organic reactions. However, in recent years, the recognition that Lewis bases can also serve in this capacity has grown enormously. Most importantly, it has become increasingly apparent that the behavior of Lewis bases as agents for promoting chemical reactions is not merely as an electronic complement of the cognate Lewis acids: in fact Lewis bases are capable of enhancing both the electrophilic and nucleophilic character of molecules to which they are bound. This diversity of behavior leads to a remarkable versatility for the catalysis of reactions by Lewis bases.
1,050 citations