- Synthesis of extended chromophores derived from 5,5-dimethyloxyluciferin by barton-kellogg methodology
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An approach to the synthesis of modified methyl ether-protected dimethyloxyluciferin derivatives is presented, focusing on the enlargement of the π-system. This was achieved by introducing an alkene bridge at the 4-position of the thiazoline moiety to lin
- Wuerfel, Hendryk,Monteiro Leite Ciscato, Luiz Francisco,Wei, Dieter,Goerls, Helmar,Beckert, Rainer
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- Mechanochromism, Twisted/Folded Structure Determination, and Derivatization of (N-Phenylfluorenylidene)acridane
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(N-Phenylfluorenylidene)acridane (Ph-FA) compounds with electron-withdrawing and -donating substituents (H, MeO, Ph, NO2, Br, F) at the para position of the phenyl group were successfully synthesized by Barton–Kellogg reactions of N-aryl thioacridones and diazofluorene. By using the substituent on the nitrogen atom to alter the electronic properties, both the folded and twisted conformers of p-NO2-C6H4-FA could be crystallographically characterized, which enabled the charge transfer from the electron-donating acridane moiety to the electron-accepting fluorenylidene moiety to be understood. Ground-state mechanochromism, thermochromism, vapochromism, and proton-induced chromism were demonstrated between the folded and twisted conformations of the conformers. Protonation and chemical oxidation of Ph-FA gave two stable acridinium compounds, namely, the fluorenylacridinium and acridinium radical cations. The present study will contribute to the development of functional dyes and organic semiconductors.
- Matsuo, Yutaka,Wang, Ya,Ueno, Hiroshi,Nakagawa, Takafumi,Okada, Hiroshi
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p. 8762 - 8767
(2019/05/29)
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- Trifluoromethylation and Monofluoroalkenylation of Alkenes through Radical–Radical Cross-Coupling
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The first visible-light-induced trifluoromethylation and monofluoroalkenylation of simple alkenes via a challenging radical–radical cross-coupling step was achieved. This method provided a mild, step-economical and redox-neutral route to privileged two different fluorinated difunctionalized allyl compounds. The utility of this method is illustrated by late-stage modification of medically important molecules.
- Wang, Qiang,Qu, Yi,Tian, Hao,Liu, Yuxiu,Song, Hongjian,Wang, Qingmin
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p. 8686 - 8690
(2019/06/17)
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- Efficient synthesis of ferrocifens and other ferrocenyl-substituted ethylenes: Via a 'sulfur approach'
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Stable and non-odorous alkyl ferrocenyl thioketones react with bis(4-methoxyphenyl)diazomethane according to the 'two-fold extrusion' reaction principles, and tetrasubstituted ethylenes obtained thereby can be demethylated to give (Fc,2OH)-ferrocifens in good yields. The method offers an alternative approach to this class of medically relevant compounds. A similar protocol with alkyl ferrocenyl thioketones and selected diaryldiazomethanes leads to ferrocenyl-substituted ethylenes including dibenzofulvenes. These products are of potential interest for electrochemical and photophysical studies.
- Mlostoń, Grzegorz,Hamera-Fa?dyga, Róza,Celeda, Ma?gorzata,Heimgartner, Heinz
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p. 4350 - 4356
(2018/06/21)
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- Continuous Flow Synthesis and Purification of Aryldiazomethanes through Hydrazone Fragmentation
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Electron-rich diazo compounds, such as aryldiazomethanes, are powerful reagents for the synthesis of complex structures, but the risks associated with their toxicity and instability often limit their use. Flow chemistry techniques make these issues avoidable, as the hazardous intermediate can be used as it is produced, avoiding accumulation and handling. Unfortunately, the produced stream is often contaminated with other reagents and by-products, making it incompatible with many applications, especially in catalysis. Herein is reported a metal-free continuous flow method for the production of aryldiazomethane solutions in a non-coordinating solvent from easily prepared, bench-stable sulfonylhydrazones. All by-products are removed by an in-line aqueous wash, leaving a clean, base-free diazo stream. Three successful sensitive metal-catalyzed transformations demonstrated the value of the method.
- Lévesque, éric,Laporte, Simon T.,Charette, André B.
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p. 837 - 841
(2017/01/14)
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- PROTEIN DERIVATIZATION TO ENDOW CELL PENETRATION
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Methods and reagents for enhancing cellular uptake of a cargo molecule by covalently bonding optionally-substituted fluorenyl groups to the cargo molecules, where cellular uptake includes at least partial uptake into the cytosol. Useful fluorenylation reagents include those of formula: and salts thereof where variables are as defined. Cargo molecules include peptides and proteins. Also provided are fluorenylated cargo molecules, including fluorenylated peptides and proteins.
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Paragraph 0095;0099;0100
(2016/04/20)
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- New applications of hetaryl thioketones for the synthesis of hetaryl-substituted ethenes via 'two-fold extrusion reaction'
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A series of aryl/hetaryl thioketones was applied for the reactions with aryl/hetaryldiazomethanes yielding, after elimination of N2, the corresponding thiiranes. The relatively unstable dihetaryldiazomethanes were generated in situ from the corresponding hydrazones by oxidation with DMSO. The obtained thiiranes were converted into tetraaryl/hetaryl-substituted ethenes in good yields by desulfurization performed with tris(diethylamino)phosphine ((Et2N)3P).
- Mlostoń, Grzegorz,Urbaniak, Katarzyna,Pawlak, Aneta,Heimgartner, Heinz
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p. 127 - 139
(2017/03/14)
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- Fluorogenic Strain-Promoted Alkyne-Diazo Cycloadditions
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Fluorogenic reactions, in which non- or weakly fluorescent reagents produce highly fluorescent products, are attractive for detecting a broad range of compounds in the fields of bioconjugation and material sciences. Herein, we report that a dibenzocyclooctyne derivative modified with a cyclopropenone moiety (Fl-DIBO) can undergo fast strain-promoted cycloaddition reactions under catalyst-free conditions with azides, nitrones, nitrile oxides, as well as mono- and disubstituted diazo-derivatives. Although the reaction with nitrile oxides, nitrones, and disubstituted diazo compounds gave cycloadducts with low quantum yield, monosubstituted diazo reagents produced 1H-pyrazole derivatives that exhibited an approximately 160-fold fluorescence enhancement over Fl-DIBO combined with a greater than 10 000-fold increase in brightness. Concluding from quantum chemical calculations, fluorescence quenching of 3H-pyrazoles, which are formed by reaction with disubstituted diazo-derivatives, is likely due to the presence of energetically low-lying (n,π?) states. The fluorogenic probe Fl-DIBO was successfully employed for the labeling of diazo-tagged proteins without detectable background signal. Diazo-derivatives are emerging as attractive reporters for the labeling of biomolecules, and the studies presented herein demonstrate that Fl-DIBO can be employed for visualizing such biomolecules without the need for probe washout.
- Friscourt, Frédéric,Fahrni, Christoph J.,Boons, Geert-Jan
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p. 13996 - 14001
(2015/09/28)
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- gem-Difluoroolefination of Diazo Compounds with TMSCF3 or TMSCF2Br: Transition-Metal-Free Cross-Coupling of Two Carbene Precursors
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A new olefination protocol for transition-metal-free cross-coupling of two carbene fragments arising from two different sources, namely, a nonfluorinated carbene fragment resulting from a diazo compound and a difluorocarbene fragment derived from Ruppert-Prakash reagent (TMSCF3) or TMSCF2Br, has been developed. This gem-difluoroolefination proceeds through the direct nucleophilic addition of diazo compounds to difluorocarbene followed by elimination of N2. Compared to previously reported Cu-catalyzed gem-difluoroolefination of diazo compounds with TMSCF3, which possesses a narrow substrate scope due to a demanding requirement on the reactivity of diazo compounds and in-situ-generated CuCF3, this transition-metal-free protocol affords a general and efficient approach to various disubstituted 1,1-difluoroalkenes, including difluoroacrylates, diaryldifluoroolefins, as well as arylalkyldifluoroolefins. In view of the ready availability of diazo compounds and difluorocarbene reagents and versatile transformations of 1,1-difluoroalkenes, this new gem-difluoroolefination method is expected to find wide applications in organic synthesis.
- Hu, Mingyou,Ni, Chuanfa,Li, Lingchun,Han, Yongxin,Hu, Jinbo
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p. 14496 - 14501
(2015/11/27)
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- Tuning the rotation rate of light-driven molecular motors
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Overcrowded alkenes are among the most promising artificial molecular motors because of their ability to undergo repetitive light-driven unidirectional rotary motion around the central C=C bond. The exceptional features of these molecules render them highly useful for a number of applications in nanotechnology. Many of these applications, however, would benefit from higher rotation rates. To this end, a new molecular motor was designed, and the isomerization processes were studied in detail. The new motor comprises a fluorene lower half and a five-membered-ring upper half; the upper-half ring is fused to a p-xylyl moiety and bears a tert-butyl group at the stereogenic center. The kinetics of the thermal isomerization was studied by low-temperature UV-vis spectroscopy as well as by transient absorption spectroscopy at room temperature. These studies revealed that the tert-butyl and p-xylyl groups in the five-membered-ring upper half may be introduced simultaneously in the molecular design to achieve an acceleration of the rotation rate of the molecular motor that is larger than the acceleration obtained by using either one of the two groups individually. Furthermore, the new molecular motor retains unidirectional rotation while showing remarkably high photostationary states.
- Bauer, Jurica,Hou, Lili,Kistemaker, Jos C. M.,Feringa, Ben L.
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p. 4446 - 4455
(2014/06/09)
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- Substituted diaryldiazomethanes and diazofluorenes: Structure, reactivity and stability
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The synthesis of several substituted diaryldiazomethanes and diazofluorenes, and an assessment of their structure, reactivity and stability, is reported.
- Davis, Philip J.,Harris, Lawrence,Karim, Aman,Thompson, Amber L.,Gilpin, Martin,Moloney, Mark G.,Pound, Matthew J.,Thompson, Claire
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supporting information; experimental part
p. 1553 - 1556
(2011/04/26)
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- Enantioselective palladium-catalyzed carbozincation of cyclopropenes
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A highly enantioselective palladium-catalyzed carbozincation of cyclopropenes has been developed. The intermediate cyclopropylzinc species, after transmetalation with copper, were trapped with various electrophiles. This one-pot procedure furnished functionalizied cyclopropenes with excellent diastereo-and enantioselectivity.
- Kraemer, Katja,Leong, Paul,Lautens, Mark
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supporting information; experimental part
p. 819 - 821
(2011/04/24)
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- Mass migration on a polymer surface caused by photoinduced molecular rotation
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We demonstrated the formation of a photoinduced surface relief grating using thin films comprising a photochromic molecular motor, 9-(2-phenyl-2,3- dihydro-cyclopenta[a]naphthalen-1-ylidene)-9H-fluorene. Results show that mass migration occurred by patter
- Okano, Kunihiko,Ogino, Shohei,Kawamoto, Masuki,Yamashita, Takashi
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supporting information; experimental part
p. 11891 - 11893
(2011/12/15)
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- PREPARATION OF DIAZO AND DIAZONIUM COMPOUNDS
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A method for making diazo-compounds, diazonium salts thereof and other protected forms of these compounds. Diaz-compounds are prepared by reaction of a tertiary phosphine reagent carrying a reactive carbonyl group with an azide. The reaction can also generate an acyl triazene which can be converted thermally or by addition of base to form the diazo-compound or the acyl triazene can be isolated. The method is particularly useful for conversion of azides carrying one or more electron withdrawing groups to diazo-compounds. The method can be carried out in aqueous medium under mild conditions and is particularly useful for conversion of azido sugars to diazo-compound and diazonium salts thereof under physiological conditions. Tertiary phosphine reagents, particularly those that are water-soluble, and precursors for preparation of the reagents are provided.
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Page/Page column 32
(2010/06/13)
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- Synthesis of dihydroindolizines for potential photoinduced work function alteration
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Seeking to immobilize photochromophores on metallic surfaces, we have synthesized four molecules which contain both a photoresponsive dihydroindolizine (DHI) core and a sulfur containing moiety, which allow for their assembly onto gold substrates. Sonogashira, Suzuki, or Ullmann couplings are employed to generate pyridines with pendant thioacetates (or disulfides). The pyridines are condensed with spiro[2-cyclopropene-1, 9′-[9H]fluorene]- 2, 3-dimethyl ester affording the targeted DHIs.
- Bartucci, Matthew A.,Wierzbicki, Patrycja M.,Gwengo, Chengeto,Shajan, Sunny,Hussain, Syed H.,Ciszek, Jacob W.
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p. 6839 - 6842
(2011/03/18)
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- CATALYSTS FOR METATHESIS REACTIONS
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Novel catalysts for metathesis reactions, in particular for the metathesis of nitrile rubber, are provided.
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Page/Page column 15-16
(2009/04/24)
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- Mimicking the biological activity of diazobenzo[b]fluorene natural products with electronically tuned diazofluorene analogs
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Under appropriate electronic modulation, simple diazofluorene analogs recapitulate the DNA cleavage activity of kinamycin D under thiol-based reducing conditions. Achieving DNA cleavage under these reducing conditions is key to anticancer activity, as the most active compound, 1-methoxydiazofluorene, inhibits the proliferation of HeLa cells.
- Zeng, Wei,Eric Ballard,Tkachenko, Alexander G.,Burns, Virginia A.,Feldheim, Daniel L.,Melander, Christian
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p. 5148 - 5151
(2007/10/03)
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- The reaction of diazocyclopentadienyl compounds with cyclomanganated arenes as a route to ligand-appended cymantrenes
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The thermolysis of various cyclomanganated arenes in the presence of 5-diazocyclopentadiene, 7-diazoindene or 9-diazofluorene afforded the corresponding arenes tethered with cymantrenyl, benzocymantrenyl or dibenzocymantrenyl groups in fair to good yields. This reaction implies a multi-facetted mechanism that consists of three steps: the insertion of an alkylidene moiety into a C-Mn bond, a CAr-C bond formation and several haptotropic ring-slippages. The coupling reaction has proven to be particularly efficient with Mn(CO)4 chelates derived from acetylarenes and nitrogen-containing heterocycles. In one case of a 2-phenyl-2-oxazoline complex, the coupling with 9-diazofluorene yields a new η1-dibenzocymantrene complex in which the Mn(CO)4 moiety is chelated and is part of a six-membered metallacycle. The results of this study are mainly supported by the molecular structures of nine new complexes obtained by X-ray diffraction analyses. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
- Djukic, Jean-Pierre,Michon, Christophe,Heiser, Dirk,Kyritsakas-Gruber, Nathalie,De Cian, Andre,Doetz, Karl Heinz,Pfeffer, Michel
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p. 2107 - 2122
(2007/10/03)
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- Catalytic olefination of carbonyl compounds. Effect of the structure of the carbonyl compound on the reaction
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The mechanism of the novel reaction of catalytic olefination of carbonyl compounds was studied. The reaction involves the transformation of hydrazones of aromatic aldehydes and ketones into the corresponding dichloroalkenes and symmetrical azines by the treatment with carbon tetrachloride in the presence of CuCl as a catalyst. The stability of intermediate diazoalkanes is the main factor determining the direction of the reaction. In the case of sufficiently stable diazoalkanes, other products can be formed under the reaction conditions along with the products of catalytic olefination.
- Korotchenko,Shastin,Nenaidenko,Balenkova
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p. 492 - 497
(2007/10/03)
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- 4,5-Diazafluorene-based Overcrowded Alkene: A New Ligand for Transition Metal Complexes
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matrix presented A new ligand system, where a 4,5-diazafluorene-type chelate and a methoxybenzoxanthene unit are coupled by a double bond has been synthesized and fully characterized including X-ray structure. The synthesis and UV-vis spectra of Ru(II), O
- Querol, Manel,Stoekli-Evans, Helen,Belser, Peter
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p. 1067 - 1070
(2007/10/03)
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- The reaction of cyclopentadienylidine, fluorenylidene and tetrachlorocyclopentadienylidene with alcohols. A laser flash photolysis study
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Rate constants of reaction of cyclopentadienylidene, fluorenylidene and tetrachlorocyclopentadienylidene with alcohols and other quenchers were determined by laser flash photolysis methods. The rate constants of reaction of cyclopentadienylidene and fluorenylidene with various alcohols were determined and found to increase with increasing alcohol acidity. Alcohols as a group reacted faster with cyclopentadienylidene and fluorenylidene than likely ylide formers such as pyridine, ethyl acetate and tetrahydrofuran. Bronsted plots of the reaction of cyclopentadienylidene and fluorenylidene with alcohols are linear with slopes of 0·061 and 0·082, respectively. In the case of tetrachlorocyclopentadienylidene, an ylide type of reaction mechanism with alcohols is indicated. Tetrachlorocyclopentadienylidene reacts most rapidly with the least acidic alcohol studied and this carbene reacts more rapidly with tetramethylurea, pyridine and tetrahydrofuran than with methanol.
- Olson, David R.,Platz, Matthew S.
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p. 759 - 769
(2007/10/03)
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- A CONVENIENT SYNTHESIS OF DIAZO COMPOUNDS BY CATALYTIC DEHYDROGENATION OF HYDRAZONES WITH COBALT SCHIFF BASE COMPLEX-OXYGEN SYSTEM
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Cobalt Schiff base complex catalyzed oxidation of hydrazones is found to be a convenient method for the synthesis of diazo compounds.
- Nishinaga, Akira,Yamazaki, Shigekazu,Matsuura, Teruo
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p. 505 - 506
(2007/10/02)
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- Reactivity of Carbenes and Related Compounds towards Molecular Nitrogen
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The thermal N2 exchange of a number of 15N-labelled diazo compounds was studied in solution.The compounds involved were 3-diazo-1-methylindolin-2-one (1), 9-diazafluorene (2), 5-diazo-1,3-cyclopentadiene-1,2,3,4-tetracarbonitrile (3), 2-diazo-2H-imidazole-4,5-dicarbonitrile (4), 4-diazocyclohexa-2,5-dienone (5), and the conjugate acids of 4 and 5, namely 4,5-dicyano-1H-imidazole-2-diazonium ion (6) and 4-hydroxybenzenediazonium ion (7).Only 1, 4, 6, and 7 exchange their diazo group with 'external' molecular N2.The results are explained on the hypothesis that only organic species which have an empty ? orbital and which are effective in ? electron back-donation are able to react with N2.Thus, reaction with carbenes is likely to occur only if the carbene is in the 1A2 singlet state and if its electrophilicity is high.
- Grieve, Duncan M. A.,Lewis, Graham E.,Ravenscroft, Michael D.,Skrabal, Peter,Sonoda, Takaaki,et al.
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p. 1427 - 1443
(2007/10/02)
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- THE REACTIONS OF FLUORENYLIDENE WITH HETEROATOMIC NUCLEOPHILES
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The reaction of fluorenylidene with heteroatomic nucleophiles gives good yields of addition products.The rates of these reactions were determined using laser spectrophotometric techniques.Kinetic and product isotope effects were measured.The results of this investigation show that the reaction of the carbene with the nucleophile is not a one-step process.The implication of these conclusions to the spin selective reactions of carbenes and their utility as photoaffinity labels is discussed.
- Zupancic, Joseph J.,Grasse, Peter B.,Lapin, Stephen C.,Schuster, Gary B.
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p. 1471 - 1478
(2007/10/02)
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- CHEMISTRY AND KINETICS OF ARYL CARBENES IN METHANOL AT LOW TEMPERATURES.
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The chemistry and kinetics of six aryl carbenes in polycrystalline methanol are reported. The kinetics were monitored by triplet ESR spectroscopy. Isotope effects were used heavily to probe reaction mechanisms. Several analogues to solution chemistry and kinetics were found. It is concluded that the singlet-triplet energy separation decreases as DBS greater than DPC greater than DBT greater than NC greater than Fl greater than DMA.
- Wright,Platz
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p. 4175 - 4180
(2007/10/02)
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- A New Method for Preparation of Diaryldiazomethanes
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The scope of a new method of preparing diazoalkanes using m-chloroperoxybenzoic acid in an alkaline biphasic solvent system is outlined through the preparation of some diaryldiazomethanes from the appropriate hydrazones.
- Handoo, Kishan L.,Handoo, Sudesh K.
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p. 699 - 700
(2007/10/02)
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