6068-70-8Relevant academic research and scientific papers
Monooxomolybdenum(IV) complex with extremely bulky dithiolate ligands - Acceleration of O-atom transfer by distorted square pyramidal conformation
Baba, Koji,Okamura, Taka-Aki,Yamamoto, Hitoshi,Yamamoto, Tetsuo,Ohama, Mitsuo,Ueyama, Norikazu
, p. 44 - 45 (2005)
Q2[MoIVO{1,2-S2-3,6-(Ph 3CCONH)2C6H2}2] (Q = NEt4 (1), PPh4 (2)) was synthesized and characterized as a model for Mo-enzymes. The crystal structu
Chiral Triphenylacetic Acid Esters: Residual Stereoisomerism and Solid-State Variability of Molecular Architectures
Prusinowska, Natalia,Czapik, Agnieszka,Kwit, Marcin
, p. 6433 - 6448 (2021/05/29)
We have proven the usability and versatility of chiral triphenylacetic acid esters, compounds of high structural diversity, as chirality-sensing stereodynamic probes and as molecular tectons in crystal engineering. The low energy barrier to stereoisomer i
N-Ammonium Ylide Mediators for Electrochemical C-H Oxidation
Saito, Masato,Kawamata, Yu,Meanwell, Michael,Navratil, Rafael,Chiodi, Debora,Carlson, Ethan,Hu, Pengfei,Chen, Longrui,Udyavara, Sagar,Kingston, Cian,Tanwar, Mayank,Tyagi, Sameer,McKillican, Bruce P.,Gichinga, Moses G.,Schmidt, Michael A.,Eastgate, Martin D.,Lamberto, Massimiliano,He, Chi,Tang, Tianhua,Malapit, Christian A.,Sigman, Matthew S.,Minteer, Shelley D.,Neurock, Matthew,Baran, Phil S.
supporting information, p. 7859 - 7867 (2021/05/26)
The site-specific oxidation of strong C(sp3)-H bonds is of uncontested utility in organic synthesis. From simplifying access to metabolites and late-stage diversification of lead compounds to truncating retrosynthetic plans, there is a growing need for new reagents and methods for achieving such a transformation in both academic and industrial circles. One main drawback of current chemical reagents is the lack of diversity with regard to structure and reactivity that prevents a combinatorial approach for rapid screening to be employed. In that regard, directed evolution still holds the greatest promise for achieving complex C-H oxidations in a variety of complex settings. Herein we present a rationally designed platform that provides a step toward this challenge using N-ammonium ylides as electrochemically driven oxidants for site-specific, chemoselective C(sp3)-H oxidation. By taking a first-principles approach guided by computation, these new mediators were identified and rapidly expanded into a library using ubiquitous building blocks and trivial synthesis techniques. The ylide-based approach to C-H oxidation exhibits tunable selectivity that is often exclusive to this class of oxidants and can be applied to real-world problems in the agricultural and pharmaceutical sectors.
Automated Assembly of Starch and Glycogen Polysaccharides
Delbianco, Martina,Seeberger, Peter H.,Zhu, Yuntao
supporting information, p. 9758 - 9768 (2021/06/30)
Polysaccharides are Nature's most abundant biomaterials essential for plant cell wall construction and energy storage. Seemingly minor structural differences result in entirely different functions: cellulose, a β (1-4) linked glucose polymer, forms fibrils that can support large trees, while amylose, an α (1-4) linked glucose polymer forms soft hollow fibers used for energy storage. A detailed understanding of polysaccharide structures requires pure materials that cannot be isolated from natural sources. Automated Glycan Assembly provides quick access to trans-linked glycans analogues of cellulose, but the stereoselective installation of multiple cis-glycosidic linkages present in amylose has not been possible to date. Here, we identify thioglycoside building blocks with different protecting group patterns that, in concert with temperature and solvent control, achieve excellent stereoselectivity during the synthesis of linear and branched α-glucan polymers with up to 20 cis-glycosidic linkages. The molecules prepared with the new method will serve as probes to understand the biosynthesis and the structure of α-glucans.
Synthesis of Aminated Phenanthridinones via Palladium/Norbornene Catalysis
Abel-Snape, Xavier,Whyte, Andrew,Lautens, Mark
supporting information, p. 7920 - 7925 (2020/11/02)
An ortho-amination, ipso-C-H arylation mediated by palladium/norbornene cooperative catalysis is reported. This reaction proceeds through a sequential intermolecular C-N bond formation process followed by intramolecular C-H activation of a tethered arene. The products, aminated phenanthridinones, were generated in moderate to good yields. This method is also applicable to the formation of dibenzazepinones.
Straightforward formation of carbocations from tertiary carboxylic acids: Via CO release at room temperature
Bartalucci, Niccolò,Pampaloni, Guido,Marchetti, Fabio,Bortoluzzi, Marco,Zacchini, Stefano
supporting information, p. 1574 - 1577 (2019/04/02)
We report an unprecedented mode of reactivity of carboxylic acids. A series of tertiary carboxylic acids, containing at least one phenyl α-substituent, undergo loss of carbon monoxide at room temperature (295 K), by a one pot reaction with 0.5-1 molar equivalents of WCl6 in dichloromethane. A plausible mechanism for the Ph3CCO2H/WCl6 reaction, leading to [CPh3][WOCl5] and Ph3CCl, is proposed on the basis of DFT calculations. The analogous reactions involving CEt(Ph)2CO2H, CMe(Ph)2CO2H and CMe2(Ph)CO2H selectively afforded stable hydrocarbons (alkene or indene, depending on the case), apparently resulting from the rearrangement of elusive tertiary carbocations.
Decarbonylation of phenylacetic acids by high valent transition metal halides
Bartalucci, Niccolò,Marchetti, Fabio,Zacchini, Stefano,Pampaloni, Guido
, p. 5725 - 5734 (2019/05/10)
Triphenylacetic acid underwent unusual decarbonylation when allowed to react with a series of halides of group 4-6 metals in their highest oxidation state, in dichloromethane at ambient temperature. Thus, the reaction of CPh3COOH with MoCl5, in 1:1 molar ratio, afforded the trityl salt [CPh3][MoOCl4], 1, in 79% yield, while the 1:2 reaction of CPh3COOH with NbF5 afforded [CPh3][NbF6], 2, in 70% yield, NbOF3 being the metal co-product. CPh3COOH reacted with NbCl5, TiF4 and WOCl4 to give mixtures of compounds, however the cation [CPh3]+ was NMR identified in each case. [CPh3][NbCl6], 3, was isolated from NbCl5 and CPh3COCl, prior to being generated from CPh3COOH and PCl5. The reaction of CPh3COOH with TiCl4 was non-selective, and the salt [CPh3][Ti2Cl8(μ-κ2-O2CCPh3)], 4, was obtained in 18% yield. The decarbonylation reactions of CMePh2COCl and CMe2PhCOCl by means of NbCl5 led to the indanes 5a-b, which were isolated in 79-97% yields after hydrolysis of the mixtures and subsequent alumina filtration of the organic phases. The reactions of CH(Ph)2COOH with NbCl5 and WCl6 afforded NbCl4(OOCCHPh2), 6, and CHPh2COCl, respectively, as the prevalent species. CPh2(CH2CH2Br)COOH did not undergo CO release when allowed to interact with WCl6, instead selective intramolecular condensation to C(Ph)2C(O)OCH2CH2, 7, occurred. MeCCCOOH underwent hydrochlorination by WCl6 to give MeC(Cl)CHCOOH, 8, in 72% yield. All the products were fully characterized by elemental analysis, IR and multinuclear NMR spectroscopy. In addition, the solid state structures of 1, 2, 4, 7, and 8 were elucidated by X-ray diffraction.
Axially Chiral Dibenzazepinones by a Palladium(0)-Catalyzed Atropo-enantioselective C?H Arylation
Newton, Christopher G.,Braconi, Elena,Kuziola, Jennifer,Wodrich, Matthew D.,Cramer, Nicolai
supporting information, p. 11040 - 11044 (2018/07/31)
Atropo-enantioselective C?H functionalization reactions are largely limited to the dynamic kinetic resolution of biaryl substrates through the introduction of steric bulk proximal to the axis of chirality. Reported herein is a highly atropo-enantioselective palladium(0)-catalyzed methodology that forges the axis of chirality during the C?H functionalization process, enabling the synthesis of axially chiral dibenzazepinones. Computational investigations support experimentally determined racemization barriers, while also indicating C?H functionalization proceeds by an enantio-determining CMD to yield configurationally stable eight-membered palladacycles.
Amide-Directed C?H Sodiation by a Sodium Hydride/Iodide Composite
Huang, Yinhua,Chan, Guo Hao,Chiba, Shunsuke
supporting information, p. 6544 - 6547 (2017/05/29)
A new protocol for amide-directed ortho and lateral C?H sodiation is enabled by sodium hydride (NaH) in the presence of either sodium iodide (NaI) or lithium iodide (LiI). The transient organosodium intermediates could be transformed into functionalized aromatic compounds.
Triphenylacetic acid amides: Molecular propellers with induced chirality
Prusinowska, Natalia,Bendziska-Berus, Wioletta,Jelecki, Maciej,Rychlewska, Urszula,Kwit, Marcin
supporting information, p. 738 - 749 (2015/01/30)
The combination of electronic circular dichroism spectroscopy (ECD), X-ray diffraction, and theoretical calculations permitted a detailed description of an unexpected chirality transfer in triphenylacetamides, which is achieved solely through weak intramolecular interactions. The observed phenomenon proceeds as a cascade process. The triphenylacetamide chromophore is sensitive to even small changes in the relative size of the substituent attached to the stereogenic center. Substitution at the stereogenic center influences helicity of the distal trityl chromophore but does not affect its propeller shape. Deformation of the propeller shape and consequent loss of its C3 symmetry results mainly from substitution of the amide hydrogen and is connected with an increase in steric hindrance. As an outcome of our studies, a model of optical activity of chiral triphenylacetamides is proposed. The performed X-ray studies revealed that this novel class of chiral compounds is likely to be of additional value due to the porosity of the crystals.
