2380-36-1Relevant articles and documents
Synthesis and Reactivity of Iron Complexes with a Biomimetic SCS Pincer Ligand
Speelman, Amy L.,Skubi, Kazimer L.,Mercado, Brandon Q.,Holland, Patrick L.
supporting information, p. 1965 - 1974 (2021/02/01)
Recent experimental evidence suggests that the FeMoco of nitrogenase undergoes structural rearrangement during N2 reduction, which may result in the generation of coordinatively unsaturated iron sites with two sulfur donors and a carbon donor. In an effort to synthesize and study small-molecule model complexes with a one-carbon/two-sulfur coordination environment, we have designed two new SCS pincer ligands containing a central NHC donor accompanied by thioether-or thiolate-functionalized aryl groups. Metalation of the thioether ligand with Fe(OTf)2 gives 6-coordinate complexes in which the SCS ligand binds meridionally. In contrast, metalation of the thiolate ligand with Fe(HMDS)2 gives a four-coordinate pseudotetrahedral amide complex in which the ligand binds facially, illustrating the potential structural flexibility of these ligands. Reaction of the amide complex with a bulky monothiol gives a four-coordinate complex with a one-carbon/three-sulfur coordination environment that resembles the resting state of nitrogenase. Reaction of the amide complex with phenylhydrazine gives a product with a rare κ1-bound phenylhydrazido group which undergoes N-N cleavage to give a phenylamido complex.
One-Pot Generation of Benzynes from Phenols: Formation of Primary Anilines by the Deoxyamination of Phenols
Akai, Shuji,Ikawa, Takashi,Masuda, Shigeaki
, (2020/03/23)
Benzynes were selectively generated in situ from phenols and trapped regioselectively with potassium hexamethyldisilazide to form primary anilines following acidic workup. The direct conversion of a phenolic hydroxyl group into a free amino group is a useful method for the preparation of primary aryl amines that are hard to synthesize by using coupling reactions involving phenol derivatives with ammonia. Whereas reactions of ortho- and meta-substituted phenols produced meta-substituted anilines exclusively, those of para-substituted phenols provided ortho-silylanilines.
The tris-urea motif and its incorporation into polydimethylsiloxane-based supramolecular materials presenting self-healing features
Roy, Nabarun,Buhler, Eric,Lehn, Jean-Marie
supporting information, p. 8814 - 8820 (2013/07/26)
Materials of supramolecular nature have attracted much attention owing to their interesting features, such as self-reparability and material robustness, that are imparted by noncovalent interactions to synthetic materials. Among the various structures and synthetic methodologies that may be considered for this purpose, the introduction of extensive arrays of multiple hydrogen bonds allows for the formation of supramolecular materials that may, in principle, present self-healing behavior. Hydrogen bonded networks implement dynamic noncovalent interactions. Suitable selection of structural units gives access to novel dynamic self-repairing materials by incrementing the number of hydrogen-bonding sites present within a molecular framework. Herein, we describe the formation of a tris-urea based motif giving access to six hydrogen-bonding sites, easily accessible through reaction of carbohydrazide with an isocyanate derivative. Extension towards the synthesis of multiply hydrogen-bonded supramolecular materials has been achieved by polycondensation of carbohydrazide with a bis-isocyanate component derived from poly-dimethylsiloxane chains. Such materials underwent self-repair at a mechanically cut surface. This approach gives access to a broad spectrum of materials of varying flexibility by appropriate selection of the bis-isocyanate component that forms the polymer backbone. Healing power: Easy access to a tris-urea motif, with the possibility of forming six H-bonds, has been demonstrated. This concept was further extended to the formation of soft functional materials based on polydimethylsiloxane moieties amenable to self-repair (see figure). Copyright
Dynamic Covalent chemistry: A facile room-temperature, reversible, diels-alder reaction between anthracene derivatives and n-phenyltriazolinedione
Roy, Nabarun,Lehn, Jean-Marie
supporting information; scheme or table, p. 2419 - 2425 (2012/07/03)
A series of readily accessible, dynamic Diels-Alder reactions that are reversible at room temperature have been developed between anthracene derivatives as dienes and N-phenyl-1,2,4-triazoline-3,5-dione as the dienophile. The adducts formed undergo reversible component exchange to form dynamic libraries of equilibrating cycloadducts. Furthermore, reversible adduct formation allows temperature-dependent modulation of the fluorescent properties of anthracene components; a feature of potential interest for the design of optodynamic polymeric materials by careful selection and manipulation of these simple dienes and dienophiles. Copyright
A new trigonal-bipyramidal [CuII(pytBuN3)Cl 2] complex: Synthesis, structure and ligand substitution behaviour
Shaban, Shaban Y.,Heinemann, Frank W.,Van Eldik, Rudi
experimental part, p. 3111 - 3118 (2009/10/17)
The synthesis, structure and ligand substitution mechanism of a new five-coordinate copper(II) complex with a sterically constrained pytBuN 3 chelate ligand [pytBuN3 = 2,6-bis(3,5di-tert- butylphenyliminomethyl)pyridine] are reported
Palladium-catalyzed coupling of ammonia with aryl chlorides, bromides, iodides, and sulfonates: A general method for the preparation of primary arylamines
Vo, Giang D.,Hartwig, John F.
supporting information; experimental part, p. 11049 - 11061 (2009/12/05)
We report that the complex generated from Pd[P(o-tol)3] 2 and the alkylbisphosphine CyPF-t-Bu is a highly active and selective catalyst for the coupling of ammonia with aryl chlorides, bromides, iodides, and sulfonates. The couplings of ammonia with this catalyst conducted with a solution of ammonia in dioxane form primary arylamines from a variety of aryl electrophiles in high yields. Catalyst loadings as low as 0.1 mol % were sufficient for reactions of many aryl chlorides and bromides. In the presence of this catalyst, aryl sulfonates also coupled with ammonia for the first time in high yields. A comparison of reactions in the presence of this catalyst versus those in the presence of existing copper and palladium systems revealed a complementary, if not broader, substrate scope. The utility of this method to generate amides, imides, and carbamates is illustrated by a one-pot synthesis of a small library of these carbonyl compounds from aryl bromides and chlorides, ammonia, and acid chlorides or anhydrides. Mechanistic studies show that reactions conducted with the combination of Pd[P(o-tol)3]2 and CyPF-t-Bu as catalyst occur with faster rates and higher yields than those conducted with CyPF-t-Bu and palladiun(II) as catalyst precursors because of the low concentration of active catalyst that is generated from the combination of palladium(II), ammonia, and base.
Selective palladium-catalyzed arylation of ammonia: Synthesis of anilines as well as symmetrical and unsymmetrical di- and triarylamines
Surry, David S.,Buchwald, Stephen L.
, p. 10354 - 10355 (2008/03/13)
It is shown that by selection of an appropriate palladium/ligand system, temperature, concentration, and stoichiometry of reagents, ammonia may be selectively arylated to give either anilines, symmetrical di-, or triarylamines. Furthermore different aryl halides may be added sequentially to the reaction mixture, allowing the synthesis of unsymmetrical di- and triarylamines from aryl halides and ammonia in a one-pot protocol Copyright
Aza-retinoids as novel retinoid X receptor-specific agonists
Farmer, Luc J.,Marron, Kristen S.,Canan Koch, Stacie S.,Hwang,Kallel, E. Adam,Zhi, Lin,Nadzan, Alex M.,Robertson, Dave W.,Bennani, Youssef L.
, p. 2352 - 2356 (2007/10/03)
A new structurally simple series of potent lipophilic aza-retinoids RXR agonists has been developed. SAR studies for the N-alkyl-azadienoic acids described here demonstrate that the RXR activity profile is sensitive to the N-alkyl chain length. Further, we have expanded the work to include azadienoic acids, which exhibited many accessible conformations leading to a better understanding of the SAR around the series.
VARIABLE TEMPERATURE ESR SPECTRA OF 1-(3,4,5-TRIMETHOXY-BENZOYL)-2,2-BIS(3,5-DI-TERT-BUTYL-PHENYL)HYDRAZYL AND ITS 1-(15)N-CONGENER
Crasovschi, Afanase,Grecu, Nicoleta,Negoita, Nicolae,Caproiu, Miron Teodor,Balaban, Alexandru T.
, p. 1335 - 1340 (2007/10/03)
The title free radicals were obtained by oxidation of the corresponding hydrazines which were synthesized and characterized by elemental analysis, IR and 1H-NMR spectra. The ESR spectra of the free radicals were recorded in toluene in the temperature range -50 deg C to +90 deg C. The simulated ESR spectra indicate a higher spin density at the tricoordinated N-2 nitrogen of the diarylamino group (hfc aN = 0.862 mT) than at the dicoordinated N-1 nitrogen atom (hfc aN = 0.830 mT). In the temperature range 0 deg C to 30 deg C the activation free energy for interconversion of conformers was determined to be ΔG(excit.) = 7.80 kcal/mol.
Retinobenzoic Acids. 1. Structure-Activity Relationships of Aromatic Amides with Retinoidal Activity
Kagechika, Hiroyuki,Kawachi, Emiko,Hashimoto, Yuichi,Himi, Toshiyuki,Shudo, Koichi
, p. 2182 - 2192 (2007/10/02)
Two types of aromatic amides, terephthalic monoanilides and (arylcarboxamido)benzoic acids, have been shown to possess potent retinoidal activities and can be classified as retinoids.The structure-activity relationships of these amides are discussed on the basis of differentiation-inducing activity on human promyelocytic leukemia cells HL-60.In generic formula 4 (X = NHCO or CONH), the necessary factors to elicit the retinoidal activities are a medium-sized alkyl group (isopropyl, tert-butyl, etc.) at the meta position and a carboxyl group at the para position of the other benzene ring.The bonding of the amide structure can be reversed, this moiety apparently having the role of locating the two benzene rings at suitable positions with respect to each other.Substitution at the ring position ortho to the amide group or N-methylation of the amido group caused loss of activity, presumably owing to the resultant change of conformation.It is clear that the mutual orientation of the benzylic methyl group(s) and the carboxyl group and their distance apart are essential factors determining the retinoidal activity.Among the synthesized compounds, 4-benzoic acid (Am80) and 4-benzoic acid (Am580) were several times more active than retinoic acid in the assay.They are structurally related to retinoic acid, as is clear from the biological activity of the hybrid compounds (M2 and R2).
