Xia A.-B.,Zhejiang University of Technology |
Wu C.,Zhejiang University of Technology |
Wang T.,Zhejiang University of Technology |
Zhang Y.-P.,Zhejiang University of Technology |
And 4 more authors.
Advanced Synthesis and Catalysis | Year: 2014
The efficient simultaneous activation of cyclohexenones or simple alkyl acyclic enones and 2-hydroxynitrostyrenes was realized by using a prolinol thioether catalyst. Thus, a highly chemo-, diastereo- and enantioselective synthesis of functionalized tetrahydroxanthenones and chromanes with up to three contiguous stereocenters was developed. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Cai G.R.,Taizhou College
Applied Mechanics and Materials | Year: 2014
Information technology which represented by the Internet obtained the swift and violent development, not only to the global economic, political, and cultural life, has brought strong impact, but also for in rapid growth, the world outlook and outlook on life has not really formed by college students, a large number of network information have also been widely affects their ideology, values, ways of thinking, and all aspects of daily life, to the traditional ideological and political education has brought intense impact. How to access into the information technology and the ideological and political education, to explore more effective methods of ideological and political education, the ideological and political education will be facing a major issue. © (2014) Trans Tech Publications, Switzerland.
Xu D.-Q.,Zhejiang University of Technology |
Wang Y.-F.,Zhejiang University of Technology |
Zhang W.,Zhejiang University of Technology |
Luo S.-P.,Zhejiang University of Technology |
And 3 more authors.
Chemistry - A European Journal | Year: 2010
(Figure Presented) Distance brings forth beauty: The first highly enantioselective organocatalytic Michael addition of 4-hydroxycoumarins and the analogous 4-hydroxy-6methyl-2-pyrone to β,γ-unsaturated α-keto esters by using chiral squaramides as the organocatalysts is disclosed. The efficiency of the process is attributed to the hydrogen-bonding activation (see scheme). © 2010 Wiley-VCH Verlag GmbH & Co. KGaA,.
Li B.L.,Taizhou College |
Xu D.-Q.,Zhejiang University of Technology |
Zhong A.G.,Taizhou College
Journal of Fluorine Chemistry | Year: 2012
Novel SO 3H-functionalized ionic liquids were successfully applied as catalysts for one-pot Fischer indole synthesis under microwave irradiation and in a water medium. Various types of indoles were prepared using single-carbonyl ketones/aldehydes or cyclohexandiones with aryhydrazine hydrochlorides in 86-96% yields in water under microwave irradiation. The indole products could be conveniently separated from the reaction mixture through filtration, and the catalytic system of [(HSO 3-p) 2im] [CF 3SO 3]/H 2O could be reused directly without any treatment. The entire process is simple, time saving, and environmentally friendly. © 2012 Elsevier B.V.
Huang Y.,Hunan University |
Zhong A.-G.,Taizhou College |
Yang Q.,PT TSG Chemical |
Liu S.,University of North Carolina at Chapel Hill
Journal of Chemical Physics | Year: 2011
The anomeric effect (the tendency of heteroatomic substituents adjacent to a heteroatom within the cyclohexane ring to prefer the axial orientation instead of the sterically less hindered equatorial position) is traditionally explained through either the dipole moment repulsion or the hyperconjugation effect. In this work, by employing our recent work in density functional steric analysis, we provide a novel two-component explanation, which is consistent with the common belief in chemistry that the effect has a stereoelectronic origin. With -D-glucopyranose as the prototype, we systematically explore its conformational space and generate 32 isomers, leading to a total of 80 axial-equatorial conformation pairs. The energy difference analysis of these pairs shows that while statistically speaking the tendency is valid, the anomeric effect is not always true and can be violated. Three energy components, exchange-correlation, classical electrostatic, and density functional steric, are found to be directly proportional to the total energy difference between axial and equatorial isomers. We also found that the total dipole moment change, not the hyperconjugation effect, is a reasonable indicator of the total energy difference. However, all these correlations alone are not strong enough to provide a compellingly convincing explanation for the general validity of the effect. With the help of strong correlations between energy components, an explanation with two energy components, steric and electrostatic, was proposed in this work. We show that the axial-equatorial energy difference in general, with the anomeric effect as a special case, is dictated by two factors of the stereoelectronic origin, steric hindrance and classical electrostatic interactions, synchronously working together. Another explanation in terms of exchange-correlation and electrostatic interactions has also been obtained in this work. © 2011 American Institute of Physics.