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31.
The development of an NHC-based system capable of cross-coupling sp(3)-sp(3) centers in high yield has been a long-standing challenge. This communication describes the use of a Pd-NHC catalytic system that achieves room-temperature Negishi cross-couplings of unactivated, primary bromides and alkyl organozinc reagents with a variety of functionality. [reaction: see text] 相似文献
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Arsalan Mirjafari Niloufar Mobarrez James H. Davis Jr Jalil Noei 《Comptes Rendus Chimie》2011,14(12):1065-1070
A wide variety of oximes were prepared from different types of alcohols with hydroxylamine hydrochloride using 1-methylimidaziloum nitrate, [Hmim][NO3], ionic liquid as a reaction medium and promoter under microwave irradiation. This protocol provides a one-pot oxime synthesis with high yields that is facile, eco-friendly and the ionic liquid can be recovered and reused. 相似文献
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Five new ammonium phosphinates with formula [XC6H4NHC(O)NHP(O)YO]?[H2Y]+ (Y = N(CH3)(CH2C6H5), X = H (IV), CH3 (V), NO2 (VI); Y = NH(CH2C6H5), X = H (VII), NO2 (VIII)) were synthesised by the reaction of N-arylureidophoshoryl dichlorides with N-methylbenzylamine or benzylamine in the presence of an excess amount of the corresponding amine. All new compounds were characterised by NMR and IR spectral data and elemental analysis. Their antimicrobial activity was tested against some Gram-positive and Gram-negative bacteria and fungi. Compounds IV and VIII exhibited moderate activity in vitro against Bacillus subtilis. In addition, compound VIII moderately inhibited Pseudomonas aeruginosa. The crystal structure of benzylmethylammonium(3-phenylureido)(benzylmethylamino)phosphinate (IV) was also determined. This compound crystallises in the orthorhombic system. 相似文献
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Niloufar Behin Aein Peter Wan 《Journal of photochemistry and photobiology. A, Chemistry》2009,208(1):42-49
This work reports results of further studies on a new class of excited state intramolecular proton transfer (ESIPT), from phenol OH to adjacent aromatic carbon atoms of suitably designed biphenyl systems. For this purpose, a number of 2-phenylphenols 3–6 with methyl and methoxy substituents on the adjacent proton accepting phenyl ring were synthesized. In particular, we were also interested in studying the effect of an acetyl (ketone) substituent on the proton accepting ring (biphenyl 7) and the effect on the photochemistry when the ketone is reduced to alcohol (biphenyl 8). All compounds except for 7 were found to undergo deuterium exchange (Фex = 0.019–0.079) primarily at the 2′-position on photolysis in 1:3 D2O–CH3CN. This is consistent with a reaction mechanism involving initial ESIPT from the phenol OH to the 2′-position of the adjacent phenyl ring, to generate a biphenyl quinone methide intermediate which rapidly tautomerizes back to starting material. Biphenyl 8 also undergoes a competing photosolvolysis reaction (overall loss of water). Both photosolvolysis and ESIPT reactions react via isomeric quinone methide intermediates and are best interpreted as arising from an excited singlet state that possesses a large degree of charge transfer character, from the phenol ring to the attached phenyl ring. The failure of 7 to react may be due to two possible reasons: (i) high intersystem crossing rate to a non-polarized triplet excited state and/or (ii) a polarized singlet state that is now much more basic at the carbonyl oxygen. The results are consistent with qualitative examination of calculated HOMOs and LUMOs (AM1). 相似文献
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The attempted synthesis of the 2-acetamido and 2-amino derivatives of salacinol, a naturally occurring glycosidase inhibitor, is described. Reaction of the protected acetamidothioarabinitol unit with the cyclic sulfate derived from L-erythritol gave the corresponding sulfonium sulfate, which underwent ring opening to give an acyclic amido sulfate. The corresponding reaction of the protected azidothioarabinitol unit with the cyclic sulfate proceeded to give the sulfonium sulfate. However, upon reduction of the azido function to an amine it formed an acyclic ammonium sulfate. 相似文献
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Malek Taher Maghsoodlou Nourallah Hazeri Sayyed Mostafa Habibi‐Khorassani Ghasem Marandi Lotfali Saghatforoush Danial Saravani Niloufar Akbarzadeh Torbati Faramarz Rostami‐Charati Khatereh Khandan‐Barani Brian W. Skelton Mohamed Makha 《Heteroatom Chemistry》2010,21(4):222-227
New phosphonate ester derivatives were obtained by in situ stereo‐specific reaction between triphenyl phosphite and dialkyl acetylenedicarboxylates in the presence of a series of halogenated anilines. Spectroscopic data and X‐ray crystallography analysis are in agreement with the gauche arrangement for the two vicinal protons in the structures. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 21:222–227, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20600 相似文献
38.
In this article, we consider two m1-branes at angle in the presence of the background electric fields, in a partially compact spacetime. The branes have motions
along a common direction that is perpendicular to both of them. Using the boundary state formalism, we calculate their interaction
amplitude. Some special cases of this interaction will be studied in detail. 相似文献
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Organ MG Abdel-Hadi M Avola S Hadei N Nasielski J O'brien CJ Valente C 《Chemistry (Weinheim an der Bergstrasse, Germany)》2007,13(1):150-157
An easily employed, highly versatile Kumada-Tamao-Corriu (KTC) protocol utilizing the PEPPSI (Pyridine, Enhanced, Precatalyst, Preparation, Stabilization and Initiation) precatalysts 1 and 2 is detailed. The ease-of-use of these catalysts and the synthesis of a wide range of hindered biaryls, large coupling partners and drug-like heterocycles, in high yield, makes the PEPPSI-KTC protocol very attractive. The high reactivity of the PEPPSI system allowed a tetra-ortho-substituted heterocycle, 11 to be synthesized at room temperature for the first time using any protocol. The PEPPSI protocols also tolerated the Boc protecting group and phenols required no protection in modified conditions. A relatively large scale (10 g) reaction was also performed with no loss in performance. Furthermore, PEPPSI-IPr, 1, was compared to previously reported highly active phosphine ligands 42, 43, and 44 and was shown to result in significantly better yields under identical conditions. Finally, we demonstrated that the PEPPSI catalyst system is very adept at performing sequential KTC coupling reactions, analogous to multicomponent reactions, which allow complex polyaryl and polyheteroaryl architectures to be produced in one single operation. 相似文献