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Cycloelimination of Imidazolidin‐2‐ylidene N‐Heterocyclic Carbenes: Mechanism and Insights into the Synthesis of Stable “NHC‐CDI” Amidinates 下载免费PDF全文
Aleksandr V. Zhukhovitskiy Julie Geng Prof. Dr. Jeremiah A. Johnson 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(15):5685-5688
We report the discovery that 1,3‐bis(aryl)imidazolidin‐2‐ylidenes, one of the most widely studied classes of N‐heterocyclic carbenes (NHCs), undergo quantitative conversion to zwitterionic “NHC‐CDI” amidinates upon heating to ≈100 °C in solution. The mechanism of this novel NHC decomposition process is studied in detail. These studies enabled the rational synthesis of a new class of bench stable amidinates from a panel of NHCs and carbodiimides. We expect these constructs to find utility in a variety of applications. 相似文献
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We prove that a WLD subspace of the space consisting of all bounded, countably supported functions on a set Γ embeds isomorphically into if and only if it does not contain isometric copies of . Moreover, a subspace of is constructed that has an unconditional basis, does not embed into , and whose every weakly compact subset is separable (in particular, it cannot contain any isomorphic copies of ). 相似文献
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Maywald Jacob D. Reiman Adam D. Overstreet Robert E. Johnson Alan W. 《Annals of Operations Research》2019,274(1-2):425-445
Annals of Operations Research - We consider the use of the new C-130J-30 aircraft for long distance (strategic) cargo movement. Currently, only large aircraft, the C-5 and the C-17, are identified... 相似文献
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Chris L. Vonnegut Airlia M. Shonkwiler Muhammad M. Khalifa Dr. Lev N. Zakharov Prof. Darren W. Johnson Prof. Michael M. Haley 《Angewandte Chemie (International ed. in English)》2015,54(45):13318-13322
Treatment of 2‐ethynylanilines with P(OPh)3 gives either 2,2‐diphenoxy‐2‐λ5‐phosphaquinolines or 2‐phenoxy‐2‐λ5‐phosphaquinolin‐2‐ones under transition‐metal‐free conditions. This reaction offers access to an underexplored heterocycle, which opens up the study of the fundamental nature of the N?PV double bond and its potential for delocalization within a cyclic π‐electron system. This heterocycle can serve as a carbostyril mimic, with application as a bioisostere for pharmaceuticals based on the 2‐quinolinone scaffold. It also holds promise as a new fluorophore, since initial screening reveals quantum yields upwards of 40 %, Stokes shifts of 50–150 nm, and emission wavelengths of 380–540 nm. The phosphaquinolin‐2‐ones possess one of the strongest solution‐state dimerization constants for a D–A system (130 M ?1) owing to the close proximity of a strong acceptor (P?O) and a strong donor (phosphonamidate N? H), which suggests that they might hold promise as new hydrogen‐bonding hosts for optoelectronic sensing. 相似文献
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