- One-Step Synthesis of Triphenylphosphonium Salts from (Het)arylmethyl Alcohols
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Two approaches for the synthesis of substituted phosphonium salts from easily available benzyl alcohols and their heterocyclic analogs have been developed. The developed protocols are complementary: the direct mixing of alcohol, trimethylsilyl bromide, and triphenylphosphine in 1,4-dioxane followed by heating at 80 °C was found to be more efficient for acid-sensitive substrates, such as salicyl or furfuryl alcohols as well as secondary benzyl alcohols, while a one-pot procedure including sequential addition of trimethylsilyl bromide and triphenylphosphine gave higher yields for benzyl alcohols bearing electroneutral or electron-withdrawing substituents.
- Abaev, Vladimir T.,Chalikidi, Petrakis N.,Demidov, Oleg P.,Gutnov, Andrey V.,Magkoev, Taimuraz T.,Trushkov, Igor V.,Uchuskin, Maxim G.
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p. 9838 - 9846
(2021/07/28)
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- Palladium-Catalyzed Formation of N-Heteroarenes from Nitroarenes using Molybdenum Hexacarbonyl as the Source of Carbon Monoxide
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The development of a method that employs a two-chamber reaction vessel and uses molybdenum hexacarbonyl [Mo(CO)6] as the carbon monoxide (CO) source for the palladium-catalyzed transformation of nitroarenes into indoles or imidazoles is reported.
- Zhou, Fei,Wang, Duo-Sheng,Driver, Tom G.
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supporting information
p. 3463 - 3468
(2016/01/25)
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- Ion-pairing of phosphonium salts in solution: C-H...halogen and C-H...π hydrogen bonds
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The 1HNMR chemical shifts of the C(α)-H protons of arylmethyl triphenylphosphonium ions in CD2Cl2 solution strongly depend on the counteranions X-. The values for the benzhydryl derivatives Ph2CH-PPh3+ X -, for example, range from δH=8.25 (X -=Cl-) over 6.23 (X-=BF4 -) to 5.72ppm (X-=BPh4-). Similar, albeit weaker, counterion-induced shifts are observed for the ortho-protons of all aryl groups. Concentration-dependent NMR studies show that the large shifts result from the deshielding of the protons by the anions, which decreases in the order Cl- > Br- a‰ BF4 - > SbF6-. For the less bulky derivatives PhCH2-PPh3+ X-, we also find C-H...Ph interactions between C(α)-H and a phenyl group of the BPh4- anion, which result in upfield NMR chemical shifts of the C(α)-H protons. These interactions could also be observed in crystals of (p-CF3-C6H4)CH2-PPh 3+ BPh4-. However, the dominant effects causing the counterion-induced shifts in the NMR spectra are the C-H...X- hydrogen bonds between the phosphonium ion and anions, in particular Cl- or Br-. This observation contradicts earlier interpretations which assigned these shifts predominantly to the ring current of the BPh4- anions. The concentration dependence of the 1HNMR chemical shifts allowed us to determine the dissociation constants of the phosphonium salts in CD2Cl2 solution. The cation-anion interactions increase with the acidity of the C(α)-H protons and the basicity of the anion. The existence of C-H...X- hydrogen bonds between the cations and anions is confirmed by quantum chemical calculations of the ion pair structures, as well as by X-ray analyses of the crystals. The IR spectra of the Cl- and Br- salts in CD2Cl2 solution show strong red-shifts of the C-H stretch bands. The C-H stretch bands of the tetrafluoroborate salt PhCH 2-PPh3+ BF4- in CD 2Cl2, however, show a blue-shift compared to the corresponding BPh4- salt.
- Ammer, Johannes,Nolte, Christoph,Karaghiosoff, Konstantin,Thallmair, Sebastian,Mayer, Peter,Devivie-Riedle, Regina,Mayr, Herbert
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supporting information
p. 14612 - 14630
(2013/11/06)
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- Synthesis and photoluminescent properties of new ceramidine derivatives
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A series of new ceramidine derivatives 8a-f has been synthesized in 4-5 steps involving a Wittig reaction of ceramidonine with various triphenylphosphonium bromides. Their UV and photoluminescence (PL) properties are reported. The compounds showed medium to strong PL between 502 and 522 nm at a concentration of 1 × 10-5 M CH2Cl2.
- Park, Byung Sun,Lee, Sang Woo,Kim, In Tae,Tae, Jin Sung,Lee, So Ha
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experimental part
p. 66 - 73
(2012/03/26)
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- Dirhodium(II)-catalyzed intramolecular C-H amination of aryl azides
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(Chemical Equation Presented) Azides to indoles: Dirhodium(II)-catalyzed decomposition of aryl azides was developed as a mild, functional group tolerant method for the synthesis of indoles (see scheme).
- Shen, Meihua,Leslie, Brooke E.,Driver, Tom G.
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supporting information; experimental part
p. 5056 - 5059
(2009/03/11)
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- Synthesis and evaluation of (pyridylmethylene)tetrahydronaphthalenes/- indanes and structurally modified derivatives: Potent and selective inhibitors of aldosterone synthase
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Elevated aldosterone levels are key effectors for the development and progression of congestive heart failure and myocardial fibrosis. Recently, we proposed inhibition of aldosterone synthase (CYP11B2) as an innovative strategy for the treatment of these
- Ulmschneider, Sarah,Müller-Vieira, Ursula,Klein, Christian D.,Antes, Iris,Lengauer, Thomas,Hartmann, Rolf W.
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p. 1563 - 1575
(2007/10/03)
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