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Metal Alkoxide Promoted Regio‐ and Stereoselective CO and CC Metathesis of Allenoates with Aldehydes
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Minyan Wang Dr. Zhao Fang Prof. Dr. Chunling Fu Prof. Dr. Shengming Ma 《Angewandte Chemie (International ed. in English)》2014,53(12):3214-3217
The reaction of 2,3‐allenoates and aldehydes in the presence of an alkoxide affords alkyl 4,5‐diaryl‐3‐oxo‐2‐propylpent‐4(E)‐enoates and cis‐3,4‐diaryloxetanes through a formal C?O and C?C metathesis. A mechanism for this reaction has been proposed. 相似文献
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Helmut Poleschner Reiner Radeglia Hinrich Meyer 《Magnetic resonance in chemistry : MRC》1984,22(8):480-485
This paper reports the 77Se NMR chemical shifts of 1,3-dithiole-, 1,3-thiaselenole- and 1,3-diselenole-2-ones, -thiones and -selones, of the corresponding saturated compounds 1,3-diselenolane-2-one, -thione and -selone, and the 1,3-thiaselenolium tetrafluoroborates, either unsubstituted or substituted by morpholino, ethylthio or ethylseleno groups in the 2-position. The 77Se chemical shift values of the ring selenium and the C?Se groups are compared with the 13C chemical shift values of neighbouring carbon atoms. The relationships between the 77Se chemical shifts of the C?Se groups and the wavelengths of their n→* absorption in the UV-visible spectrum are discussed with respect to the significance of the δE term in the contribution of the paramagnetic screening and the electron density distribution. 相似文献
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The reversibly formed C?N bond plays a very important role in dynamic covalent chemistry and the C?N/C?N exchange of components between different imine constituents to create dynamic covalent libraries has been extensively used. To facilitate diversity generation, we have investigated an organocatalyzed approach, using L ‐proline as catalyst, to accelerate the formation of dynamic libraries of [n×n] imine components. The organocatalysis methodology has also been extended, under somewhat modified conditions, to reversible C?C/C?N exchange processes between Knoevenagel derivatives of barbituric acid and imines, allowing for the generation of increased diversity. 相似文献
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Andrew J. Keane Wesley S. Farrell Brendan L. Yonke Peter Y. Zavalij Lawrence R. Sita 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(35):10358-10362
A highly efficient and versatile chemical cycle has been developed for the production of isocyanates through the molecular fixation of N2, CO2 and R3ECl (E=C, Si, and Ge). Key steps include a ‘one‐pot’ photolytic N N bond cleavage of a Group 6 dinuclear dinitrogen complex with in situ trapping by R3ECl to provide a metal terminal imido complex that can engage in simultaneous nitrene‐group transfer and oxygen‐atom transfer to generate an intermediate metal terminal oxo complex with release of the isocyanate product. Reaction of the oxo complex with additional equivalents of R3ECl regenerates a metal dichloride that is the precursor for dinuclear dinitrogen starting material. 相似文献
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Metal‐Mediated Production of Isocyanates,R3ENCO from Dinitrogen,Carbon Dioxide,and R3ECl
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Andrew J. Keane Wesley S. Farrell Brendan L. Yonke Peter Y. Zavalij Prof. Lawrence R. Sita 《Angewandte Chemie (International ed. in English)》2015,54(35):10220-10224
A highly efficient and versatile chemical cycle has been developed for the production of isocyanates through the molecular fixation of N2, CO2 and R3ECl (E=C, Si, and Ge). Key steps include a ‘one‐pot’ photolytic N? N bond cleavage of a Group 6 dinuclear dinitrogen complex with in situ trapping by R3ECl to provide a metal terminal imido complex that can engage in simultaneous nitrene‐group transfer and oxygen‐atom transfer to generate an intermediate metal terminal oxo complex with release of the isocyanate product. Reaction of the oxo complex with additional equivalents of R3ECl regenerates a metal dichloride that is the precursor for dinuclear dinitrogen starting material. 相似文献
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Philipp Willmes Dr. Michael J. Cowley Marco Hartmann Dr. Michael Zimmer Dr. Volker Huch Prof. Dr. David Scheschkewitz 《Angewandte Chemie (International ed. in English)》2014,53(8):2216-2220
The generation of heavier double‐bond systems without by‐ or side‐product formation is of considerable importance for their application in synthesis. Peripheral functional groups in such alkene homologues are promising in this regard owing to their inherent mobility. Depending on the steric demand of the N‐alkyl substituent R, the reaction of disilenide Ar2Si?Si(Ar)Li (Ar=2,4,6‐iPr3C6H2) with ClP(NR2)2 either affords the phosphinodisilene Ar2Si?Si(Ar)P(NR2)2 (for R=iPr) or P‐amino functionalized phosphasilenes Ar2(R2N)Si? Si(Ar)?P(NR2) (for R=Et, Me) by 1,3‐migration of one of the amino groups. In case of R=Me, upon addition of one equivalent of tert‐butylisonitrile a second amino group shift occurs to yield the 1‐aza‐3‐phosphaallene Ar2(R2N)Si? Si(NR2)(Ar)? P?C?NtBu with pronounced ylidic character. All new compounds were fully characterized by multinuclear NMR spectroscopy as well as single‐crystal X‐ray diffraction and DFT calculations in selected cases. 相似文献