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81.
In this contribution we report on fluorotrimethyl[(Z)-pentafluoropropen-1-yl]phosphorane as a phosphorus based fluorinating reagent. Its solid state structure can be described as a trigonal bipyramid featuring elongated axial bonds due to the formation of a 3-center 4-electron bond. Abstraction of the fluoride ion leads to a shortening of the axial P–C bond. Thus the title compound can be utilized for substitution of bromine with fluorine and for the transfer of fluoride ions onto electrophilic compounds. Reaction with Sn(C2F5)2Br2 afforded salt [P(CH3)3(C3F5)]2[Sn(C2F5)2F4]. When fluorotrimethyl[(Z)-pentafluoropropen-1-yl]phosphorane was treated with P(C2F5)2F the primarily produced anion is sufficiently nucleophilic to attack the propenyl group of the cation in β-position to the phosphorus atom to yield zwitterionic [Me3PCF=C(CF3)–PF3(C2F5)2]. 相似文献
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Dr. Mahendra K. Sharma Dr. Sebastian Blomeyer Beate Neumann Dr. Hans-Georg Stammler Priv.-Doz. Dr. Rajendra S. Ghadwal 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(35):8249-8253
The first divinyldiarsenes [{(NHC)C(Ph)}As]2 (NHC=IPr 3 a , SIPr 3 b ; IPr=C{(NAr)CH}2; SIPr=C{(NAr)CH2}2; Ar=2,6-iPr2C6H3) are reported. Compounds 3 a and 3 b were prepared by the reduction of corresponding chlorides {(NHC)C(Ph)}AsCl2 (NHC=IPr 2 a , SIPr 2 b ) with Mg. Calculations revealed a small HOMO–LUMO energy gap of 3.86 ( 3 a ) and 4.24 eV ( 3 b ). Treatment of 3 a with (Me2S)AuCl led to the cleavage of the As=As bond to restore 2 a , which is expected to proceed via the diarsane [{(IPr)C(Ph)}AsCl]2 ( 4 ). Remarkably, 4 as well as 2 a can be selectively accessed on treatment of 3 a with an appropriate amount of C2Cl6. Moreover, 3 a readily reacts with PhEEPh (E=Se or Te) at room temperature to give {(IPr)C(Ph)}As(EPh)2 (E=Se 5 a ; Te 5 b ), revealing the cleavage of As=As and E−E bonds and the formation of As−E bonds. Such highly selective stepwise oxidation ( 3 a → 4 → 2 a ) and bond metathesis ( 3 a → 5 a , b ) reactions are unprecedented in main-group chemistry. 相似文献
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Haoquan Li Dr. Helfried Neumann Prof. Dr. Matthias Beller 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(29):10050-10056
A benign and efficient palladium‐catalyzed aminocarbonylation reaction of allylic alcohols is presented. The generality of this novel process is demonstrated by the synthesis of β,γ‐unsaturated amides including aliphatic, cinnamyl, and terpene derivatives. The choice of ligand is crucial for optimal carbonylation processes: Whereas in most cases the combination of PdCl2 with Xantphos ( L6 ) gave best results, sterically hindered substrates performed better in the presence of simple triphenylphosphine ( L10 ), and primary anilines gave the best results using cataCXium® PCy ( L8 ). The reactivity of the respective catalyst system is significantly enhanced by addition of small amounts of water. Mechanistic studies and control experiments revealed a tandem allylic alcohol amination/C?N bond carbonylation reaction sequence. 相似文献
85.
Alexander M. Khenkin Gregory Leitus Lev Weiner Ronny Neumann 《Journal of Cluster Science》2014,25(3):687-693
The tri-rhenium(VI) capped Wells–Dawson polyoxometalate, [Re3P2W15O62]6– with quaternary ammonium cations was synthesized by reacting the trivacant lacunary species, [P2W15O56]12– with [ReOCl3(PPh3)2] in an organic solvent. Elemental analysis by thermogravimetry and inductively coupled plasma mass spectroctrometry confirmed the substitution of three rhenium atoms, single-crystal X-ray diffraction as well as infra red spectroscopy showed the complete Wells–Dawson structure. The presence of all three rhenium atoms in one cap is indicated by 31P nuclear magnetic resonance spectroscopy and the electron spin resonance spectrum shows that the tri-rhenium(V) species with three unpaired electrons is low spin, S = ½. 相似文献
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Dr. Philipp Holtkamp Dario Poier Beate Neumann Dr. Hans-Georg Stammler Prof. Dr. Norbert W. Mitzel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(11):3793-3798
The reactivity of the geminal frustrated Lewis pair (FLP) (F5C2)3SnCH2P(tBu)2 ( 1 ) was explored by reacting it with a variety of small molecules (PhOCN, PhNCS, PhCCH, tBuCCH, H3CC(O)CH=CH2, Ph[C(O)]2Ph, PhN=NPh and Me3SiCHN2), featuring polar or non-polar multiple bonds and/or represent α,β-unsaturated systems. While most adducts are formed readily, the binding of azobenzene requires UV-induced photoisomerization, which results in the highly selective complexation of cis-azobenzene. In the case of benzil, the reaction does not lead to the expected 1,2- or 1,4-addition products, but to the non-stereoselective (tBu)2PCH2-transfer to a prochiral keto function of benzil. All adducts of 1 were characterised by means of multinuclear NMR spectroscopy, elemental analyses and X-ray diffraction experiments. 相似文献
90.
Abstract Novel liquid crystalline 2-phenyl-1,3,4-thiadiazole based oligomers with three and four rigid aromatic units linked by a flexible central unit have been investigated by polarizing microscopy. The synthesis of these compounds and the influence of structural variations on the mesomorphic properties are described. The combination of suitable mesogenic moieties with appropriate central units leads to oligomers which exhibit Sc phases. 相似文献