- Cocondensation reactions of heterocyclic aromatic compounds with lithium, calcium and magnesium atoms at 77 K
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Calcium and magnesium atoms were cocondensed with aromatic heterocycles containing five- and six-membered rings in the presence of THF at 77 K. In the case of calcium the cocondensation with five-membered heterocyclic compounds resulted in C-H bond activations and led to the corresponding aryl calcium compounds, while magnesium did not show comparable reactions. When six-membered heterocyclic compounds, e.g., pyridine and 4-methylpyridine (4-picoline) were cocondensed with calcium, magnesium and lithium atoms, all reactions led to the formation of non-metallated aromatic products and the formation of metal hydride. DFT calculations at the B3LYP/6-31G** level of theory were carried out in order to interpret the pathways of the cocondensation reactions using calcium atoms and identify the possible intermediates involved. In all reactions π- and σ-complexes between calcium atoms and the heterocyclic aromatic reactant were found as stable intermediates on the energy hypersurface.
- Mendoza, Oscar,Tacke, Matthias
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- Cocondensation reactions of five-membered heterocycles with lithium atoms at 77 K
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Lithium atoms were cocondensed with eight aromatic five-membered heterocycles in the presence of THF at 77 K. In the case of the oxygen- and sulfur-containing heterocycles (furans and thiophenes), the reaction resulted in C-H bond activation and led to the corresponding aryllithium compound. The other heterocycles (pyrroles) failed to react with lithium atoms in the presence of THF. A special case was found when oxazole was reacted under these cocondensation conditions; here a dilithiated product was obtained. DFT (B3LYP/6-31G **) calculations were carried out in order to interpret the pathways of the reactions and the possible intermediates. For all the reactions π- and o-complexes between lithium clusters and the heterocycles were found as stable intermediates. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
- Mendoza, Oscar,Rehmann, Franz-Josef K.,Cuffe, Laurence P.,Tacke, Matthias
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- Electrophilic 2-thienylselenenylation of thiophene. Preparation of oligo(seleno-2,5-thienylenes)
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The substitution reactions of thiophene and 2-methylthiophene with the electrophilic selenenylating agent produced from the 2,2'-dithienyl diselenide by oxidation with iodobenzene diacetate involve only the α- positions and give rise to the formation of oligo(seleno-2,5-thienylenes). Products deriving from the attack at the α-positions of thiophene and 2- methylthiophene were also observed starting from the 5,5'-dimethyl-2,2'- dithienyl diselenide. The same electrophilic reagents reacted with furan and 2-methylfuran to afford a mixture of the mono- and di-substituted compounds. (C) 2000 Elsevier Science Ltd.
- Tiecco, Marcello,Testaferri, Lorenzo,Bagnoli, Luana,Marini, Francesca,Temperini, Andrea,Tomassini, Cristina,Santi, Claudio
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- Thiophenylazobenzene: An Alternative Photoisomerization Controlled by Lone-Pair???π Interaction
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Azoheteroarene photoswitches have attracted attention due to their unique properties. We present the stationary photochromism and ultrafast photoisomerization mechanism of thiophenylazobenzene (TphAB). It demonstrates impressive fatigue resistance and photoisomerization efficiency, and shows favorably separated (E)- and (Z)-isomer absorption bands, allowing for highly selective photoconversion. The (Z)-isomer of TphAB adopts an unusual orthogonal geometry where the thiophenyl group is perfectly perpendicular to the phenyl group. This geometry is stabilized by a rare lone-pair???π interaction between the S atom and the phenyl group. The photoisomerization of TphAB occurs on the sub-ps to ps timescale and is governed by this interaction. Therefore, the adoption and disruption of the orthogonal geometry requires significant movement along the inversion reaction coordinates (CNN and NNC angles). Our results establish TphAB as an excellent photoswitch with versatile properties that expand the application possibilities of AB derivatives.
- Slavov, Chavdar,Yang, Chong,Heindl, Andreas H.,Wegner, Hermann A.,Dreuw, Andreas,Wachtveitl, Josef
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- Rhodium-Catalyzed Intermolecular Silylation of Csp?H by Silacyclobutanes
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The signature reactivity of silacyclobutane (SCB) is their cycloaddition reactions with various π bonds. Recently, the first cases were disclosed where SCBs reacted with both Csp2?H and Csp3?H σ bonds in an intramolecular fashion. Herein, it is reported that SCB is also an efficient reagent for Csp?H bond silylation. Thus, rhodium-catalyzed intermolecular reactions between SCBs and terminal alkynes produced a series of symmetrical and unsymmetrical tetraorganosilicons bearing a Csp?Si functionality. Preliminary studies suggested that the reaction did not involve a cycloaddition pathway, but instead a direct activation of Csp?H bonds.
- He, Tao,Li, Bin,Liu, Lichuan,Ma, Wenpeng,He, Wei
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supporting information
p. 5648 - 5652
(2021/03/08)
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- Synthesis of Benzosiloles by Intramolecular anti-Hydroarylation via ortho-C-H Activation of Aryloxyethynyl Silanes
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Straightforward synthesis of benzosiloles was achieved by the invention of Pd/acid-catalyzed intramolecular anti-hydroarylation of aryloxyethynyl(aryl)silanes via ortho-C-H bond activation. The aryloxy group bound to the ethynyl carbon is the key factor for this transformation.
- Minami, Yasunori,Noguchi, Yuta,Hiyama, Tamejiro
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supporting information
p. 14013 - 14016
(2017/10/17)
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- LIPIDIC FURAN, PYRROLE, AND THIOPHENE COMPOUNDS FOR USE IN THE TREATMENT OF ATROPHIC VAGINITIS
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Provided herein are lipidic furan, pyrrole, and thiophene compounds, compositions, and methods using such compounds and compositions for the treatment of atrophic vaginitis. Specifically, the invention includes administering an effective amount of a compound of Formula I, I′, or I″, or a pharmaceutically acceptable composition, salt, isotopic analog, prodrug, or combination thereof, to a subject suffering from atrophic vaginitis.
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Paragraph 0181; 0182; 0183; 0184; 0185
(2017/11/16)
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- Chemoselective Ketone Synthesis by the Addition of Organometallics to N-Acylazetidines
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A general and highly chemoselective method for the synthesis of ketones by the addition of organometallics to N-acylazetidines via stable tetrahedral intermediates is reported for the first time. The transformation is characterized by its wide substrate scope and exquisite selectivity for the ketone products even when a large excess of nucleophilic reagents is used. Even of broader interest is the use of N-acylazetidines as bench-stable, readily available amide acylating reagents, in which the reactivity is controlled by amide pyramidalization and strain of the four-membered ring to afford synthetically valuable building blocks.
- Liu, Chengwei,Achtenhagen, Marcel,Szostak, Michal
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supporting information
p. 2375 - 2378
(2016/06/09)
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- Is carbon dioxide able to activate halogen/lithium exchange?
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The unexpected effect of carbon dioxide on halogen-lithium exchange (HLE) reactions of selected haloarenes with tBuLi was investigated. In an aliphatic hydrocarbon solvent (pentane), the HLE does not occur at ca. -70 C but, surprisingly, pouring the mixture of reactants onto dry ice and subsequent aqueous acidic hydrolysis gave carboxylic acids resulting from the quench of the first-formed aryllithiums with carbon dioxide. This suggests that CO 2 acts as a promoter of the HLE and, subsequently, serves as an electrophile to trap the aryllithium intermediates that are generated in situ. Theoretical DFT calculations were used to develop a plausible mechanism for the reaction, which indicates that CO2 is a much weaker donor than tetrahydrofuran (THF) so the cleavage of inert tBuLi cubic tetramers into more reactive solvated dimeric species (tBuLi)2(CO2) 4 is disfavored by 42.8 kJ per mol of (tBuLi)4. It is possible that this deaggregation process occurs to some extent when a large excess of CO2 is used. Copyright
- Durka, Krzysztof,Lulinski, Sergiusz,Dabrowski, Marek,Serwatowski, Janusz
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p. 4562 - 4570
(2014/08/05)
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- Synthetic routes to fluorescent dyes exhibiting large stokes shifts
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Derivatives of isomeric 2-(hydroxytolyl)-4,6-dimethylamino-1,3,5-triazines have been synthesized in high yields in a controlled manner using a multistep reaction sequence. Iodination of either 2-(1′-hydroxy-6′-methylphen- 2′-yl)- or 2-(1′-hydroxy-4′-methylphen-2′-yl)-4,6- dimethylamino-1,3,5-triazine with ICl provides species differing in the positioning of the iodo group relative to the hydroxyl which readily undergo Suzuki, Sonogashira, and Heck reactions under Pd(0) catalysis. Thus, thienyl, bisthienyl, and 3,4-ethylenedioxythienyl groups have been directly grafted, while unsubstituted polycyclic aromatics such as pyrene and perylene have been linked via alkyne bridges, as have ethynyldifluoroborondipyrromethane (BODIPY) dyes prepared in situ. The presence of a hydrogen bond in the ground state involving the hydroxyl substituent has been established by proton NMR and several X-ray structure determinations. All of the new dyes with a simple substituent (phenyl, thienyl) exhibited a pronounced green fluorescence resulting from an intramolecular proton transfer in the excited state (ESIPT) which produces a large Stokes shift (>10 000 cm-1). With other dyes, the fluorescence of the keto form responsible for the ESIPT process could be used as the input energy in efficient intramolecular energy transfer processes. Replacing perylene with pyrene allowed reversal of the direction of energy transfer from the polyaromatic module to the keto form.
- Rihn, Sandra,Retailleau, Pascal,De Nicola, Antoinette,Ulrich, Gilles,Ziessel, Raymond
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p. 8851 - 8863
(2013/01/15)
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- SEC-HYDROXYCYCLOHEXYL DERIVATIVES AS HSL INHIBITORS FOR THE TREATMENT DIABETES
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The invention provides novel compounds having the general formula (I) wherein R1, R2 and R3 are as described herein, and compositions including the compounds. The use of the compounds as inhibitors of hormone sensitive lipose (HSL) for the treatment of diseases such as diabetes and metabolic symdrome is also disclosed.
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Page/Page column 31
(2012/10/07)
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- Solution structure and chelation properties of 2-thienyllithium reagents
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The solution and chelation properties of 2-thienyllithium reagents with potential amine and ether chelating groups in the 3-position and related model systems have been investigated using low temperature 6Li, 7Li, 13C, and 31P NMR spectroscopy, 15N-labeling, and the effect of solvent additives. In THF-ether mixtures at low temperature 3-(N,N-dimethylaminomethyl)-2-thienyllithium (4) is ca. 99% dimer (which is chelated) and 1% monomer (unchelated), whereas 3-(methoxymethyl)-2-thienyllithium (5) is 10% dimer. Compound 5 crystallizes as a THF-solvated dimer, but there is no indication that the ether side chain is chelated in solution. Both 4 and 5 form PMDTA-complexed monomers almost stoichiometrically, similar to the model compound 2, in sharp contrast to phenyl analogues, which show very different behavior. The barriers to dimer interconversion are ca. 2 kcal/mol lower and chelation is significantly weaker in the 2-thienyllithium reagents than in their phenyl analogues.
- Jantzi, Kevin L.,Puckett, Craig L.,Guzei, Ilia A.,Reich, Hans J.
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p. 7520 - 7529
(2007/10/03)
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- Ethylene trimerization with a half-sandwich titanium complex bearing a pendant thienyl group
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A half-sandwich titanium complex with a pendant thienyl group, activated by methylalumoxane (MAO), can trimerize ethylene to 1-hexene with considerable activity and high selectivity; the coodination of the sulfur atom to the titanium center is proposed to be responsible for the selective trimerization of ethylene.
- Huang, Jiling,Wu, Tianzhi,Qian, Yanlong
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p. 2816 - 2817
(2007/10/03)
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- O- or S- substituted tetrahydronaphthalene derivatives having retinoid and/or retinoid antagonist-like biological activity
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Compounds of the formula where the symbols have the meaning described in the application, have retinoid-like or retinoid antagonist-like biological activity.
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Page column 75-76
(2010/11/29)
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- NMR studies on derivatives of heteroaromatic compounds: Exceptionally small carbon-carbon couplings, 1JCC, in 2-lithiothiophene, 2-lithio-N-methylpyrrole and 2-lithiofuran
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Spin-spin carbon-carbon coupling constants across one bond and carbon-proton coupling constants across one, two and three bonds have been measured for a large series of derivatives of five-membered heterocyclic compounds. This included 2-methyl and 2-lithio derivatives of furan, N-methyl pyrrole and thiophene and a series of 2-R-substituted thiophenes where R = O-t-Bu, Cl, Br, I, Si(CH3)3, MgBr and MgTh. For the long-range C-H couplings their signs have been determined in several compounds by the use of modern 2D NMR techniques, and in all the cases they have been found to be positive. A good linear dependence upon electronegativity of the substituent has been observed for 1JCC, 2JC2H3 and 3JC2H4. Very small 1JCC couplings of ca. 30 Hz only have been found in all three lithio compounds; they belong to the smallest couplings of this type reported up to now. They are accompanied by very large and positive two-bond couplings, 2JC2H3 of ca. +20 Hz, which in turn are the largest couplings of this type reported so far. In both cases the changes observed are interpreted in terms of the changes in the Fermi contact contribution.
- Dabrowski, Andrzej,Kamienska-Trela, Krystyna,Wojcik, Jacek
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- Oxa-and thia-diazole muscarinic receptor antagonists
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A compound of formula (I) STR1 wherein R 1 is C 1-6 alkyl, halo-(C 1-6 alkyl), C 3-7 cycloalkyl, C 2-6 alkylnyl, hydroxy-(C 2-6 alkylnyl), (C 1-4 alkoxy)-(C 2-6 alkylnyl), aryl, aryl-(C 1-4 alkyl), heteroaryl or heteroaryl-(C 1-4 alkyl); R 2 is H or C 1-4 alkyl; R 3 is aryl, heteroaryl, 2,3-dihydrobenzofuranyl or C 4-7 cycloalkyl; X is O or S; Y is bond, --CH 2 --, --(CH 2) 2 -- or --CH 2 O--, a pharmaceutically acceptable salt thereof, which are useful muscarinic receptor antagonists in treaatment of e.g. irritable bowel syndrome, urinary incontinence, etc.
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- Oxime substituted tetrahydronaphthalene derivatives having retinoid and/or retinoid antagonist-like biological activity
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Compounds of the formula STR1 have retinoid-like or retinoid antagonist-like biological activity.
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- Direct Preparation of 3-Thienyl Organometallic Reagents: 3-Thienylzinc and 3-Thienylmagnesium Iodides and 3-Thienylmanganese Bromides and Their Coupling Reactions
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3-Thienylzinc and 3-thienylmagnesium iodides can be generated from the direct oxidative addition of Rieke zinc and magnesium to 3-iodothiophene, respectively. The direct preparation of 3-thienylmanganese bromides from the reaction of Rieke manganese with 3-bromothiophene and 3,4-dibromothiophene is also performed. These 3-thienyl organometallic reagents have been found to be regiostable intermediates and undergo coupling reactions with a variety of versatile electrophiles such as acid chlorides, aryl iodides, aldehydes, and disulfide.
- Rieke, Reuben D.,Kim, Seung-Hoi,Wu, Xiaoming
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p. 6921 - 6927
(2007/10/03)
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- Transmetalations from zirconium to copper intermediates
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Higher order cuprate complexes are prepared by means of a transmetalation from a corresponding zirconate intermediate. This process is particularly valuable with respect to the preparation of vinylic side chains such as are present in prostaglandins, as it is possible in accordance with the present invention to proceed directly from the acetylenic precursors via the reactive cuprates to the desired final products in a one-pot operation without isolation of intermediates and in high yields. Sequential additions to zirconium intermediates of components which together comprise the cuprate involved in transmetalation with the zirconium intermediate are disclosed as alternative procedures.
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- Synthesis of Quinolinequinones and 1,2,3,4-Tetrahydroquinolinequinones via Cyclobutenediones
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N-Benzyl-1,2,3,4-tetrahydrocyclobutapyridine-5,6-dione is easily synthesized and functions as a synthetic equivalent of the unstable pyridiocyclobutenedione.Regiospecific introduction of unsaturated nucleophiles at the more reactive carbonyl group, followed by thermolysis in xylene in vessels open to air, rapidly establishes the tetrahydroquinolinequinone system which can be oxidized to the corresponding quinolinequinone with 2,3-dichloro-5,6-dicyanoquinone.
- Liebeskind, Lanny S.,Zhang, Jing
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p. 6379 - 6385
(2007/10/02)
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- Substituted thienylethylamines and process for their production
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Substituted thienylethylamines of the formula: STR1 wherein R is formyl, acetyl or benzoyl or is benzyl, which is ring-substituted by at least one halogen atom, and R1 is a lower alkyl, phenyl or substituted phenyl, are initial products for the production of antithrombolytically effective pharmaceutical agents. A process for the production of the above-mentioned compounds from substituted ethanolamines by their reaction with strong bases, further reaction with the resultant aziridines with 2-thienyllithium, and conversion of the resultant thienylethylamines with compounds of formula RX, wherein R has the above-mentioned meaning and X is a halogen.
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- Stereoselective Synthesis of 2Z,4E-Dienals by Addition of Organometallic Reagents to Pyrylium Perchlorate
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A facile and stereoselective approach to 2Z,4E-dienals and derived products is presented.The method involves addition of an organometallic reagent to a pyrylium salt, followed by electrocyclic ring-opening of the intermediate 2H-pyran, to give the desired Z,E-dienal, usually with greater than 95percent stereochemical purity.These dienals may be trapped in situ with a second organometallic reagent, or oxidised or redused, without loss of stereochemical integrity.The synthesis of (1,3Z,5E)-undeca-1,3,5-triene, a component of the essential oils of the brown Hawaiian seaweeds Dictyopteris plagiogramma and D. australis, is reported to illustrate the simplicity of the procedure.
- Furber, Mark,Herbert, John M.,Taylor, Richard J. K.
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p. 683 - 690
(2007/10/02)
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