The catalytic behaviour of the superbases Na/NaOH/-Al2O3 and CsxO/-Al2O3 as well as of the basic zeolites Na/NaX and CsxO/CsX were investigated in the Michael addition of ethyl acrylate and acetone. The reactions were carried out in the liquid phase at catalyst loadings varying from 0.05 to 0.1 mol ester/g catalyst. 相似文献
Cinchonidine and cinchonine have been grafted onto pure silica MCM-41. It has been shown that both supported alkaloids are active catalysts for the Michael addition of ethyl 2-oxocyclopentanecarboxylate and methyl vinyl ketone, anchored cinchonidine being more active and enantioselective than anchored cinchonine. The study of the influence of the polarity of the solvent and reaction temperature on the optical induction shows that there is not a direct correlation between solvent polarity and enantioselectivity, and the maximum optical yield was obtained between 278 and 273 K. 相似文献
Bromomethyl and chloromethyl (E)-β-styryl sulfones enter a Michael ring closure reaction with sodium enolates prepared from dimethyl malonate, malononitrile and ethyl acetoacetate. The condensation results in formation of substituted tetrahydrothiophene-S,S-dioxides. It is a new instance of α-haloalkyl sulfones transformations, which are not connected with Ramberg–Bäcklund reaction. 相似文献
The dissolution of the conventional breaking points in the construction and completion phases of a building's delivery has blurred ‘the distinction between the production of design intent and the transmission of information’. Here Richard Garber , Director of the School of Architecture at the New Jersey Institute of Technology (NJIT), advocates that architects should use this as an opportunity to widen their remit, gaining agency and with it responsibility and the financial rewards to practice. Here he draws from the examples of UNStudio, GLUCK+ and his own New-York based practice, GRO Architects. 相似文献
Shifting the focus from futuristic visions, Alfredo Brillembourg and Hubert Klumpner with Alexis Kalagas of interdisciplinary design practice Urban-Think Tank urge us to ‘forget about utopia’, for in the most part the urban environment of 2050 is already built. Architects’ sights need to be set on the sometimes grim and unfolding reality of favelas and the world's informal cities. 相似文献
How might architectural thinking and processes shift over the next 35 years? How might the architect's role be redefined with shifting ethical values? Could the architect be viewed as less of a design professional and more of a curator engaged in the development of healthy holistic environments, catering for all of society's needs? DaeWha Kang , an architect from 2050, writes to his earlier self, critiquing the work that he undertook in independent practice and as a design director at Zaha Hadid Architects in the mid-2010s. He describes how his design methodologies have evolved in the intervening years. 相似文献
A dual catalytic system has been developed following the screening of a series of chiral primary amine catalysts and chiral phosphoric acid catalysts for the Michael addition of cyclic ketones to nitroolefins bearing only one α‐substituent. The resulting γ‐nitro ketones, which contain a substituent on the carbon connected to the nitro group, were formed in excellent yields (>80%) with high levels of stereoselectivity (up to 94:6 dr and 98% ee) when the reaction was performed in benzene at 0 °C with 10 mol% of the optimal amine/phosphoric acid combination (1:1) as a catalyst. Subsequent reduction of the nitro group followed by intramolecular reductive amination could afford optically active cis‐octahydroindole analogues bearing a non‐functional substituent at their 2‐position.