- Towards the isomer-specific synthesis of higher fullerenes and buckybowls by the surface-catalyzed cyclodehydrogenation of aromatic precursors
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Fullerenes on a plate: A surface-catalyzed cyclodehydrogenation reaction enabled selective fullerene-cage formation from polycyclic organic precursors. As no C-C bond rearrangement occurred during the reaction, only specifically designed precursors gave the desired fullerene (see picture). This efficient and selective condensation process opens new horizons in the directed synthesis of fullerenes and related structures. Copyright
- Amsharov, Konstantin,Abdurakhmanova, Nasiba,Stepanow, Sebastian,Rauschenbach, Stephan,Jansen, Martin,Kern, Klaus
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Read Online
- INHIBITORS OF MTOR-MEDIATED INDUCTION OF AUTOPHAGY
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The invention provides amides that inhibit apoptosis or induce autophagy through mTOR-mediated induction of autophagy, or inhibit a related disease such as cerebral ischemia/reperfusion or neurodegenerative diseases, including corresponding sulfonamides, and pharmaceutically acceptable salts, hydrates and stereoisomers thereof. The compounds are employed in pharmaceutical compositions, and methods of making and use, including treating a person in need thereof with an effective amount of the compound or composition, and detecting a resultant improvement in the person's health or condition.
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Paragraph 088
(2021/04/30)
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- Chiral Ligand-Mediated Nucleophilic Aromatic Substitution of Naphthoic Acids: A Fast and Efficient Access to Axially Chiral Biaryls
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A transition metal-free synthesis of enantioenriched biaryls from aryllithium species has been developed. This approach relies on atropoenantioselective nucleophilic aromatic substitution (SNAr) reaction of unprotected naphthoic acids. The ability of a diverse set of chiral ligands to mediate this transformation has been investigated. 1,2-diether ligands outperform their diamine counterparts and the best enantiocontrol was obtained with readily accessible enantiopure trans-1,2-dimethoxycyclohexane. This SNAr reaction offers an efficient and rapid access to enantioenriched binaphthalenes, phenylnaphthalene, and phenanthrylnaphthalenes (up to 94:6 er).
- Nguyen, Thi Thanh Thuy,Guyon, Hélène,Nguyen, Kim Phi Phung,Boussonnière, Anne,Mortier, Jacques,Castanet, Anne-Sophie
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supporting information
p. 3829 - 3833
(2020/05/25)
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- Environmentally benign electrophilic and radical bromination 'on water': H2O2-HBr system versus N-bromosuccinimide
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A H2O2-HBr system and N-bromosuccinimide in an aqueous medium were used as a 'green' approach to electrophilic and radical bromination. Several activated and less activated aromatic molecules, phenylsubstituted ketones and styrene were efficiently brominated 'on water' using both systems at ambient temperature and without an added metal or acid catalyst, whereas various non-activated toluenes were functionalized at the benzyl position in the presence of visible light as a radical activator. A comparison of reactivity and selectivity of both brominating systems reveals the H2O2-HBr system to be more reactive than NBS for benzyl bromination and for the bromination of ketones, while for electrophilic aromatic substitution of methoxy-substituted tetralone it was higher for NBS. Also, higher yields of brominated aromatics were observed when using H2O2-HBr 'on water'. Bromination of styrene reveals that not just the structure of the brominating reagent but the reaction conditions: amount of water, organic solvent, stirring rate and interface structure, play a key role in defining the outcome of bromination (dibromination vs bromohydroxylation). In addition, mild reaction conditions, a straightforward isolation procedure, inexpensive reagents and a lower environment impact make aqueous brominating methods a possible alternative to other reported brominating protocols.
- Podgor?ek, Ajda,Stavber, Stojan,Zupan, Marko,Iskra, Jernej
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experimental part
p. 4429 - 4439
(2009/10/09)
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- A concise synthesis of novel naphtho[a]carbazoles and benzo[c]carbazoles
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Starting from simple indole precursors the synthesis of naphtho[a]carbazoles and benzo[c]carbazoles is described. Key steps include the use of the Suzuki-Miyaura reaction to afford 2- or 3-aryl substituted indoles, as well as a potassium t-butoxide and light assisted aromatic ring-forming reaction.
- Pathak, Rakhi,Nhlapo, Johanna M.,Govender, Sameshnee,Michael, Joseph P.,Van Otterlo, Willem A. L.,De Koning, Charles B.
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p. 2820 - 2830
(2007/10/03)
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- Thiophenes as traps for benzyne. 3. Diaryl sulfides and the role of dipolar intermediates
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The reactions of seven thiophenes with benzyne generated from diphenyliodonium-2-carboxylate (DPIC) under a standard set of conditions led among other products to the formation of α- and β-naphthyl phenyl sulfides 2a and 2b from thiophene (1a) and of 2c: and 2d from 2-methylthiophene (1b). Dithienyl sulfides 4a-f were produced from the halothiophenes 1c-g. The structures of the naphthyl sulfides were proven by comparison with authentic samples of 2a-f, thus eliminating one of two possible mechanisms of formation. The remaining mechanism involves [4+2]-cycloaddition of benzyne to thiophene or to an S-phenylthiophenium ylide 10 to give the dipolar 2:1 benzyne/thiophene adduct 8 followed by ring-opening. Stevens-like rearrangements of 11, formed from 10 by proton transfer, may also explain the origin of arylated thiophenes such as 12 and 3 found in some reactions of benzynes with thiophene.
- Reinecke, Manfred G.,Del Mazza, Dario,Obeng, Marcus
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- A Convergent Method for the Synthesis of Highly Enantiomerically Enriched Cyclic Silanes with Silicon-Centered Chirality
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A preparatively straightforward methodology has been developed which allows the assembly of silicon-containing carbocycles as mixtures of diastereomers with silicon as the sole center of stereogenic information. One-step construction of the chiral cyclic silanes is realized by reaction of equimolar amounts of a dibromide and a chirally modified dichlorosilane under Barbier conditions giving access to several monofunctionalized 1-sila-1,2,3,4-tetrahydronaphthalenes and a corresponding phenanthrene derivative. Facile large scale syntheses of 3-(2-bromoaryl)propyl bromides as well as dichlorosilanes have been elaborated. This highly convergent methodology relies on the novel (-)-menthyloxy-substituted dichlorosilanes, which have the chiral auxiliary for the subsequent optical resolution installed. These enantiopure dichlorosilanes are useful building blocks for a general and modular one-step approach to silanes with silicon-centered chirality since this strategy avoids the linear sequences reported in literature. The optical resolution has been exemplarily optimized for the 1-phenyl-1-sila-1,2,3,4- tetrahydronaphthalene derivative and the absolute configuration has been established by X-ray crystallography. The chiral auxiliary is stereospecifically displaced by simple reduction providing the highly enantioenriched silane (er = 98:2) which is enantiospecifically chlorinated as verified by a Walden inversion at silicon.
- Oestreich, Martin,Schmid, Ulrike K.,Auer, Gertrud,Keller, Manfred
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p. 2725 - 2739
(2007/10/03)
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- Electron Paramagnetic Resonance Spectra of Substituted 1- and 2-Naphthylmethyl Radicals
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The EPR spectra of 7-tert-butyl-1-naphthylmethyl and 6-tert-butyl-2-naphthylmethyl radicals, prepared by photolysis of the hydrocarbon with tert-butyl peroxide at -40 deg C, have been analysed by correlation methods: average α(C-H) coupling constants are 15.0 and 15.25 G respectively, in line with the expected relative stabilities of the two radicals and the recently reported stabilization energy for 1-naphthylmethyl.
- Jackson, Richard A.,Rhodes, Christopher J.
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- Preparation of biaryl compounds
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A method for the preparation of biaryl compounds is disclosed which comprises contacting an aromatic halide in the presence of a catalyst comprising zerovalent nickel, a bidentate phosphorus-containing coordinating ligand and a reducing metal in a polar, aprotic solvent system for a time and under conditions suitable for the formation of biaryl compound.
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