- Complexes of [(dadi)Ti(L/X)]m That Reveal Redox Non-Innocence and a Stepwise Carbene Insertion into a Carbon-Carbon Bond
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The addition of donors to (dadi)Ti(THF) (1-THF, dadi = [{-CH=N(1,2-C6H4)N(2,6-iPr2-C6H3)}2]n) afforded the adducts [(dadi)Ti(L/X)]m (1-L, m = 0, N2CPh2; m = -1, X = Cl-, N3-, OiPr-, CH3-, neoPe-, CH=CH2-, CCPh-, CCTMS-, H(D)-). In all adducts, the chelate was in the (dadi)4- redox state. For certain anions, evidence for intimate binding of the Li+ counterion was explored spectroscopically. Treatment of 1-THF with PhHCN2, yielded {PhC3H3(-NC6H4-2-NAr)2}Ti(THF) (3, Ar = 2,6-iPr2-C6H3), which contains a cyclopropanated dadi ligand. The mechanism was explored by calculations, and the addition of Ph2CN2 to 3 produced a nacnac derivative, {PhC(CHNC6H4-2-NAr)2}Ti(??2-HNNCPh2) (4, Ar = 2,6-iPr2-C6H3), generated via hydrogen transfer from the cyclopropane.
- Heins, Spencer P.,Morris, Wesley D.,Cundari, Thomas R.,MacMillan, Samantha N.,Lobkovsky, Emil B.,Livezey, Nicholas M.,Wolczanski, Peter T.
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Read Online
- Stereospecific synthesis of trans-2,3-diaryl substituted 1-aminocyclopropanecarboxylic acid derivatives
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The stereospecific syntheses of trans-2,3-diaryl-l-aminocyclopropanecarboxylic acid derivatives are reported. They key step is a 1,3-dipolar cycloaddition of phenyldiazomethane to (Z)-2-phenyl-4-arylidene-5(4H)-oxazolones, followed by the extrusion of nitrogen in situ.
- Su, Guifa,Mu, Hongtao,Za, Danming,Zeng, Longmei,Cativiela, Carlos,Hammer, Robert P.,Yu, Kaibei
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Read Online
- 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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- PROCESS FOR THE CYCLOADDITION OF A HETERO(ARYL) 1,3-DIPOLE COMPOUND WITH A (HETERO)CYCLOALKYNE
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A process is provided, comprising reacting a (hetero)aryl 1,3-dipole compound with a (hetero)cycloalkyne, wherein the (hetero)aryl 1,3-dipole compound comprises a 1,3-dipole functional group bonded to a (hetero)aryl group, and wherein the (hetero)aryl 1,3-dipole compound is a (hetero)aryl azide or a (hetero)aryl diazo compound; wherein: (i) the (hetero)aryl group of the (hetero)aryl 1,3-dipole compound comprises a substituent (ii) the (hetero)aryl group of the (hetero)aryl 1,3-dipole compound is an electron-poor (hetero)aryl group and wherein the (hetero)cycloalkyne is a (hetero)cyclooctyne or a (hetero)cyclononyne according to Formula (1). The invention also relates to the products obtainable by the process according to the invention.
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Paragraph 0415
(2017/01/26)
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- Cyclopropane compound as well as preparation method and application thereof
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The invention discloses a cyclopropane compound as well as a preparation method and application thereof. The cyclopropane compound has a structure shown as formula I. The cyclopropane compound is prepared by taking a diazo compound and unsaturated ketone
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Paragraph 0056; 0066-0068
(2017/08/19)
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- Preparation method of mild diazomethane derivative
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The invention discloses a preparation method of a mild diazomethane derivative. The preparation method comprises that EWG-substituted benzene sulfonyl chloride and hydrazine hydrate undergo a reaction to produce EWG-substituted benzene sulfonyl chloride, the EWG-substituted benzene sulfonyl chloride and aldehyde or ketone undergo a reaction to produce EWG-substituted benzenesulfonylhydrazone, and the EWG-substituted benzenesulfonylhydrazone, a base and an organic solvent are mixed and undergo a replacement reaction to produce a diazomethane derivative. The diazomethane derivative is not separated and purified and is further used for a tension small ring synthesis reaction and an insertion reaction. The benzene ring of benzenesulfonylhydrazone is introduced with an electron-withdrawing group EWG, and through electron effects and steric hindrance effects, the benzenesulfonyl group on the benzenesulfonylhydrazone is easily separated so that a diazomethane derivative is produced under very mild conditions and especially at the room temperature.
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Paragraph 0115; 0119
(2017/08/28)
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- Benzylic Ammonium Ylide Mediated Epoxidations
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A high yielding synthesis of stilbene oxides using ammonium ylides has been developed. It turned out that the amine leaving group plays a crucial role as trimethylamine gives higher yields than DABCO or quinuclidine. The amine group also influences the diastereoselectivity, and detailed DFT calculations to understand the key parameters of these reactions have been carried out.
- Roiser, Lukas,Robiette, Rapha?l,Waser, Mario
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supporting information
p. 1963 - 1968
(2016/08/10)
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- The p: K a of Br?nsted acids controls their reactivity with diazo compounds
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We study the O-alkylation of phosphate groups by alkyl diazo compounds in a range of small molecules and biopolymers. We show that the relatively high pKa of phosphate in comparison to the other naturally occurring Br?nsted acids can be exploited to control alkylation selectivity. We provide a simple protocol for chemical modification of some of the most important instances of phosphates in natural compounds including in small molecule metabolites, nucleic acids, and peptides.
- Fei, Na,Sauter, Basilius,Gillingham, Dennis
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supporting information
p. 7501 - 7504
(2016/06/14)
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- SMALL MOLECULE LFA-1 INHIBITORS
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The present invention relates to novel compounds which are capable of inhibiting the interaction of LFA-1 with its counter ligands.
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Page/Page column 117
(2016/01/01)
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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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supporting information
p. 13996 - 14001
(2015/09/28)
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- Improved zinc-catalyzed simmons-smith reaction: Access to various 1,2,3-trisubstituted cyclopropanes
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The Simmons-Smith reaction of zinc carbenoids with alkenes is a powerful method to access cyclopropanes containing various substitution patterns. This work exploits the high reactivity of aryldiazomethanes toward zinc halides to generate aryl-substituted carbenoids catalytically. These carbenoids are able to cyclopropanate various alkenes diastereoselectively, including unfunctionalized substrates such as styrenes. The zinc catalyst can be modified to tolerate the use of free allylic alcohols.
- Levesque, Eric,Goudreau, Sebastien R.,Charette, Andre B.
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supporting information
p. 1490 - 1493
(2014/04/03)
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- A facile one pot synthesis of substituted pyrazole derivatives
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Diazo compounds derived from aromatic aldehydes were reacted with derivatives of (Z)-2-arylidene-2H-benzofuran- 3-ones to give new highly substituted heterocyclic pyrazoles. The structures of the synthesised compounds were determined on the basis of their
- Haouas, Amel,Hamadi, Naoufel Ben,Nsira, Asma,Msadek, Moncef
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p. 435 - 437
(2013/09/12)
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- Tandem catalysis for the preparation of cylindrical polypeptide brushes
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Here, we report a method for synthesis of cylindrical copolypeptide brushes via N-carboxyanhydride (NCA) polymerization utilizing a new tandem catalysis approach that allows preparation of brushes with controlled segment lengths in a straightforward, one-pot procedure requiring no intermediate isolation or purification steps. To obtain high-density brush copolypeptides, we used a "grafting from" approach where alloc-α-aminoamide groups were installed onto the side chains of NCAs to serve as masked initiators. These groups were inert during cobalt-initiated NCA polymerization and gave allyloxycarbonyl-α-aminoamide-substituted polypeptide main chains. The alloc-α-aminoamide groups were then activated in situ using nickel to generate initiators for growth of side-chain brush segments. This use of stepwise tandem cobalt and nickel catalysis was found to be an efficient method for preparation of high-chain-density, cylindrical copolypeptide brushes, where both the main chains and side chains can be prepared with controlled segment lengths.
- Rhodes, Allison J.,Deming, Timothy J.
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supporting information
p. 19463 - 19467
(2013/02/21)
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- Nitrile imines: Matrix isolation, IR spectra, structures, and rearrangement to carbodiimides
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The structures and reactivities of nitrile imines are subjects of continuing debate. Several nitrile imines were generated photochemically or thermally and investigated by IR spectroscopy in Ar matrices at cryogenic temperatures (Ph-CNN-H 6, Ph-CNN-CH317, Ph-CNN-SiMe323, Ph-CNN-Ph 29, Ph3C-CNN-CPh334, and the boryl-CNN-boryl derivative 39). The effect of substituents on the structures and IR absorptions of nitrile imines was investigated computationally at the B3LYP/6-31G level. IR spectra were analyzed in terms of calculated anharmonic vibrational spectra and were generally in very good agreement with the calculated spectra. Infrared spectra were found to reflect the structures of nitrile imines accurately. Nitrile imines with IR absorptions above 2200 cm -1 have essentially propargylic structures, possessing a CN triple bond (typically PhCNNSiMe323, PhCNNPh 29, and boryl-CNN-boryl 39). Nitrile imines with IR absorptions below ca. 2200 cm-1 are more likely to be allenic (e.g., HCNNH 1, PhCNNH 6, HCNNPh 43, PhCNNCH317, and Ph3C-CNN-CPh334). All nitrile imines isomerize to the corresponding carbodiimides both thermally and photochemically. Monosubstituted carbodiimides isomerize thermally to the corresponding cyanamides (e.g., Ph-N=C=N-H 5 Ph-NH-CN 8), which are therefore the thermal end products for nitrile imines of the types RCNNH and HCNNR. This tautomerization is reversible under flash vacuum thermolysis conditions.
- Begue, Didier,Qiao, Greg Guanghua,Wentrup, Curt
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supporting information; experimental part
p. 5339 - 5350
(2012/05/20)
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- Olefin cyclopropanation with aryl diazocompounds upon catalysis by a dirhodium(II) complex
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A dirhodium(II) complex with N-perfluorooctylsulfonylprolinate ligands is found to catalyze the cyclopropanation of olefins with simple aryl diazomethanes. In contrast to previously reported dirhodium(II) catalysts, the present complex works well not only with very electron-rich olefins such as enol ethers, but also with styrenes. Consequently, the present catalyst allows to prepare functionalized diarylcyclopropanes in moderate yields with good diastereoselectivity for the cis product, whereas the enantioselectivity of the reaction appears negligible.
- Verdecchia, Mirella,Tubaro, Cristina,Biffis, Andrea
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experimental part
p. 1136 - 1139
(2011/03/22)
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- An enantioselective synthesis of 2-aryl cycloalkanones by sc-catalyzed carbon insertion
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Current methods for asymmetric α-arylation require blocking groups to prevent reaction at the R0-carbon, basic conditions that promote racemization, or multistep synthesis. This work records the first catalytic enantioselective examples of the diazoalkane-carbonyl homologation reaction. Medium ring 2-aryl ketones are prepared in one step in up to 98:2 er and 99% yield from the unsubstituted lower homologue by Sc-catalyzed aryldiazomethyl insertion with simple bis- and tris(oxazoline) ligands.
- Rendina, Victor L.,Moebius, David C.,Kingsbury, Jason S.
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supporting information; experimental part
p. 2004 - 2007
(2011/07/07)
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- Structure-guided design of a methyl donor cofactor that controls a viral histone H3 lysine 27 methyltransferase activity
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vSET (a viral SET domain protein) is an attractive polycomb repressive complex 2 (PRC2) surrogate to study the effect of histone H3 lysine 27 (H3K27) methylation on gene transcription, as both catalyze histone H3K27 trimethylation. To control the enzymatic activity of vSET in vivo with an engineered S-adenosyl-l-methionine (SAM) analogue as methyl donor cofactor, we have carried out structure-guided design, synthesis, and characterization of orthogonal vSET methyltransferase mutant/SAM analogue pairs using a "bump-and-hole" strategy.
- Li, Jiaojie,Wei, Hua,Zhou, Ming-Ming
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supporting information; experimental part
p. 7734 - 7738
(2012/01/13)
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- A simple route for synthesis of 4-phospho-D-erythronate
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4-Phospho-d-erythronate is an intermediate in the synthesis of pyridoxal 5′-phosphate in some bacteria and an inhibitor of ribose 5-phosphate isomerase. Previous synthetic schemes for the preparation of 4-phospho-d-erythronate required expensive precursors and typically gave low yields. We report a straightforward synthesis of 4-phospho-d-erythronate from the inexpensive precursor d-erythronolactone in five steps with a preparatively useful yield of 22%.
- Novikov, Yehor,Copley, Shelley D.,Eaton, Bruce E.
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supporting information; experimental part
p. 1913 - 1915
(2011/04/22)
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- Elucidation of the stereochemistry of thiirane formation from a 1λ4,2-dithietane bearing two chiral carbon centers
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A tetracoordinated sulfurane bearing a 1λ4,2-dithietane moiety, whose 3- and 4-positions were chiral carbon centers, was synthesized. Its thermolysis gave the corresponding thiirane as a single diastereomer, whose configuration and stereochemis
- Kusaka, Shinpei,Kano, Naokazu,Kawashima, Takayuki
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experimental part
p. 412 - 417
(2011/07/31)
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- Catalytic reactions of carbene precursors on bulk gold metal
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Bulk gold metal powder, consisting of particles (5-50 μm) much larger than nanoparticles, catalyzes the coupling of carbenes generated from diazoalkanes (R2C=N2) and 3,3-diphenylcyclopropene (DPCP) to form olefins. It also catalyzes cyclopropanation reactions of these carbene precursors with styrenes. The catalytic activity of the gold powder depends on the nature of the gold particles, as determined by TEM and SEM studies. The reactions can be understood in terms of mechanisms that involve the generation of carbene R2C: intermediates adsorbed on the gold surface.
- Zhou, Yibo,Trewyn, Brian G.,Angelici, Robert J.,Woo, L. Keith
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supporting information; experimental part
p. 11734 - 11743
(2009/12/08)
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- A ceric ammonium nitrate N-dearylation of N-p-anisylazoles applied to pyrazole, triazole, tetrazole, and pentazole rings: Release of parent azoles. Generation of unstable pentazole, HN5/N5-, in solution
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(Chemical Equation Presented) The reaction of cerium(IV) ammonium nitrate (CAN) with a range of N-(p-anisyl)azoles in acetonitrile or methanol solvents leads to N-dearylation releasing the parent NH-azole and p-benzoquinone in comparable yields. The scope and limitations of the reaction are explored. It was successful with 1-(p-anisyl)pyrazoles, 2-(p-anisyl)-1,2,3-triazoles, 2-(p-anisyl)-2H-tetrazoles, and 1-(p-anisyl)pentazole. The dearylation renders the p-anisyl group as a potentially useful N-protecting group in azole chemistry. The azole released in solution from 1-(p-anisyl)pentazole is unstable HN5, the long-sought parent pentazolic acid. p-Anisylpentazole samples were synthesized with combinations of one, two, and three 15N atoms at all positions of the pentazole ring. The unstable HN 5/N5- produced at -40°C did not build up in the solution but degraded to azide ion and nitrogen gas with a short lifetime. The 15N-labeling of the N3- ion obtained from all samples proved unequivocally that it came from the degradation of HN 5 (tautomeric forms) and/or its anion N5- in the solution.
- Butler, Richard N.,Hanniffy, John M.,Stephens, John C.,Burke, Luke A.
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p. 1354 - 1364
(2008/04/12)
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- Direct observation of carbene and diazo formation from aryldiazirines by ultrafast infrared spectroscopy
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Ultrafast laser flash photolysis (λex = 270 nm) of phenyldiazirine produces transient infrared absorptions at 2040 and 1582 cm-1. The first band is assigned to phenyldiazomethane, and the second is assigned to singlet phenylcarbene. This assignment is consistent with DFT calculations. Diazo band integration reveals that photoisomerization from diazirine to diazo occurs within a few picoseconds of the laser pulse. The majority of carbene produced is also formed instantaneously. Copyright
- Zhang, Yunlong,Burdzinski, Gotard,Kubicki, Jacek,Platz, Matthew S.
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supporting information; experimental part
p. 16134 - 16135
(2009/05/09)
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- Diazo preparation via dehydrogenation of hydrazones with "activated" DMSO
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We report that "activated" dimethyl sulfoxide efficiently dehydrogenates hydrazones to the respective diazo species at -78°C. Under optimized conditions, triethylamine hydrochloride is removed quantitatively by vacuum filtration to provide solutions of diazo compounds. Stable diazo species can be isolated in high yield, or alternatively, the direct treatment of these solutions with carboxylic acids provides esters.
- Javed, Muhammad I.,Brewer, Matthias
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p. 1789 - 1792
(2008/02/02)
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- Synthesis and antitumor characterization of pyrazolic analogues of the marine pyrroloquinoline alkaloids: Wakayin and tsitsikammamines
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A series of aza analogues of the marine alkaloids wakayin and tsitsikammamines A and B have been synthesized. The strategy used was based on [3 + 2] cycloaddition reactions involving 3-ethylamine-indole-4,7-dione and different diazo reagents. All the comp
- Legentil, Laurent,Benel, Laurent,Bertrand, Viviane,Lesur, Brigitte,Delfourne, Evelyne
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p. 2979 - 2988
(2007/10/03)
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- Rh2(OAc)4-catalyzed formation of trans-alkenes from the reaction of aldehydes with perfluorophenyl diazomethane through tellurium ylide
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Rh2(OAc)4 can catalyze the formation of perfluorophenyl-containing trans-epoxides from the reactions of perfluorophenyl diazomethane with activated aryl aldehydes through sulfur ylide intermediate. In contrast, under the same reactio
- Zhu, Shifa,Xing, Chunhui,Pang, Wan,Zhu, Shizheng
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p. 5897 - 5900
(2007/10/03)
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- Synthesis of 1,3,4-thiadiazoles from aldehyde hydrazones
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Reaction of p-tolualdehyde hydrazone with disulfur dichloride in the presence of DBU gave 2,5-di (p-tolyl)-1,3,4-thiadiazole (1a) in 54% yield. Phenyldiazomethane also reacted with disulfur dichloride to afford 2,5-diphenyl-1,3,4-thiadiazole (1b) in 80% y
- Okuma, Kentaro,Nagakura, Kazuko,Nakajima, Yasutaka,Kubo, Kento,Shioji, Kosei
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p. 1929 - 1931
(2007/10/03)
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- Enhanced diastereoselectivity via confinement: Photoisomerization of 2,3-diphenylcyclopropane-1-carboxylic acid derivatives within zeolites
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From the perspective of asymmetric induction, the photochemistry of 24 chiral esters and amides of cis-2,3-diphenylcyclopropane-1-carboxylic acid from excited singlet and triplet states has been investigated within zeolites. The chiral auxiliaries placed
- Sivaguru,Sunoj, Raghavan B.,Wada, Takehiko,Origane, Yumi,Inoue, Yoshihisa,Ramamurthy, Vaidhyanathan
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p. 6533 - 6547
(2007/10/03)
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- Asymmetric synthesis of substituted 1-aminocyclopropane1-carboxylic acids via diketopiperazine methodology
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Diketopiperazinespirocyclopropane 12 is prepared in > 98% d.e. via the conjugate addition of a phosphorus ylide to (6S)-N, N′-bis(p-methoxybenzyl)-3-methylenepiperazine-2,5-dione 2. Deprotection and hydrolysis of adduct 12 and subsequent peptide coupling demonstrate the applicability of this methodology to the asymmetric synthesis of 1-aminocyclopropane-1-carboxylic acids for incorporation into novel peptides. A model for the high level of diastereofacial selectivity observed in the cyclopropanation reaction is presented. A highly selective asymmetric approach (> 98% d.e.) to (S)-[2,2-2H 2]-1-aminocyclopropane-l-carboxylic acid 29 is also reported via a deuterated sulfur ylide addition to acceptor 2.
- Bunuel, Elena,Bull, Steven D.,Davies, Stephen G.,Garner, A. Christopher,Savory, Edward D.,Smith, Andrew D.,Vickers, Richard J.,Watkin, David J.
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p. 2531 - 2542
(2007/10/03)
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- Azolobenzazepine derivatives as neurologically active agents
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PCT No. PCT/GB97/00592 Sec. 371 Date Sep. 3, 1998 Sec. 102(e) Date Sep. 3, 1998 PCT Filed Mar. 4, 1997 PCT Pub. No. WO97/32883 PCT Pub. Date Sep. 12, 1997The invention relates to azolobenzazepine derivatives of formula (I), wherein: X is O or S; R1, R2, R3 and R4 are independently hydrogen, perfluorolower-alkyl, halogen, nitro or cyano; and C together with the carbon atoms to which it is attached forms a 5-membered aromatic heterocycle selected from the group consisting of a pyrazol and triazole, to pharmaceutical compositions containing them and to methods for the treatment of neurological disorders utilizing them.
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- Interception of deaminatively generated benzyl carbenium ions by acetone
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Essentially free benzyl carbenium ions were generated via protonation of phenyldiazomethane with benzoic acid in acetone. Interestingly, no proton transfer occurred below -20 °C. After protonation and dediazoniation of the diazoalkane at -20 °C, the solvent was found to intercept the deaminatively generated carbocations to yield initially the corresponding O-benzyl oxonium ion and benzyl benzoate. The onium ion, however, was labile under the reaction conditions, and decomposed into a cascade of products whose concentrations as a function of time were used to trace the reaction pathway. Thus, the O-benzyl oxonium ion reacted with benzoate ion to yield (2- benzyloxy)isopropyl benzoate; subsequent decomposition of this O-benzyl-O- benzoyl ketal produced 2,2-dibenzyloxypropane (a dibenzyl ketal), 2- benzyloxypropene, and benzyl alcohol. In a related study, benzyl cations were generated via thermolyses of N-benzyl-N-nitroso-O-benzoyl hydroxylamine at 0 and -70 °C. The product distributions were found to be temperature-dependent and different from that in the PhCHN2 + PhCO2H case.
- Song, Fenhong,Darbeau, Ron W.,White, Emil H.
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p. 1825 - 1829
(2007/10/03)
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- A Study of Essentially Free Carbocations Derived via Diazonium and Oxo Diazonium Ions in the Liquid Phase
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Nitrogen- and nitrous oxide-separated ion pairs containing 4-substituted benzyl cations and carboxylate or tosylate anions were prepared by thermolysis of N-nitroso- and N-nitroamides, acidification of phenyldiazomethane, and nitrosation of N-benzyl-O-benzoylhydroxylamine. The cations were generated in benzene/toluene and benzene/anisole mixtures and were found to partition between the counterion and the solvent and between the aromatic cosolvent and benzene. A familial relationship among the methods was observed. As the cation became more reactive, the yield of solvent-derived products (SDPs) rose and the ratio of rate constants for its reaction with toluene versus benzene, kT/kB, fell. The yield of SDP also rose as the temperature was decreased and as N2 was replaced by N2O; however, kT/kB remained unchanged. Inert diluents had no effect on kT/kB but decreased hydrocarbon yield by 40% on 2-fold dilution. In the presence of reactive diluents that are converted into secondary alkylating agents, both the % hydrocarbon and kT/kB rose. These results are interpreted in terms of the intermediacy of inert-molecule-separated ion pairs (IMSIPs) in deamination. The cation reacted with benzoates and tosylates not only at the oxygens but also at the ipso carbon; subsequent decarboxylation and desulfonylation, respectively, led to diphenylmethanes. The ester/SDP ratio is introduced as a new measure of carbocation reactivity.
- Darbeau, Ron W.,White, Emu H.,Song, Fenhong,Darbeau, Nyla R.,Chou, James
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p. 5966 - 5978
(2007/10/03)
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- Laser flash photolysis study of phenylcarbene, o-tolylcarbene and mesitylcarbene
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Laser flash photolysis (LFP, XeCl, 308 nm, 20 ns) of phenyldiazomethane (PDM), o-tolydiazomethane (TDM) and mesitydiazomethane (MDM) produces phenylcarbene (PC), o-tolycarbene (TC) and mesitylcarbene (MSC), respectively. Transient spectra of PC and TC cou
- Admasu, Atnaf,Platz, Matthew S.,Marcinek, Andrzej,Michalak, Jacek,Gudmundsdottir, Anna Dora,Gebicki, Jerzy
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p. 207 - 220
(2007/10/03)
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- Process for the preparation of an oxirane, azirdine or cyclopropane
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A process for the preparation of an oxirane, aziridine or cyclopropane of formula (I) wherein, X is oxygen, NR4 or CHR5 ; R1 is hydrogen, alkyl, aryl, heteroaromatic, heterocyclic or cycloalkyl; R2 is hydrogen, alkyl, aryl, heteroaromatic, CO2 R8, CHR14 NHR13, heterocyclic or cycloalkyl; or R1 and R2 join together to form a cycloalkyl ring; R3 is hydrogen, alkyl, aryl, heteroaromatic, CO2 R8, R83 Sn, CONR8 R9 or trimethylsilyl; R4 and R5 are, independently, alkyl, cycloalkyl, aryl, heteroaromatic, SO2 R8, SO3 R8, COR8, CO2 R8, CONR8 R9 or CN, or R4 can also be P(O)(aryl)2 ; R8 and R9 are independently alkyl, aryl or arylalkyl; R13 and R14 are independently hydrogen, alkyl or aryl; the process comprising reacting a mixture of a compound of formula (II), wherein R1, R2 and X are as defined above, and a sulphide of formula SR6 R7, wherein R6 and R7 are independently alkyl, aryl or heteroaomatic, or R6 and R7 join together to form a cycloalkyl ring which optionally includes an additional heteroatom, with either (i) a metallocarbon obtainable by reacting an alkylmetal with a methane derivative of formula CHR3 X'X", wherein R3 is as defined above, and X' and X" are independently, a leaving group, or (ii) a metallocarbon obtainable by reacting a compound of formula (III), (wherein R3 may not be hydrogen) with a suitable organometallic or inorganic reagent.
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- SYNTHESE DE 1,2,3-TRIAZOLINES PAR CYCLOADDITION DIPOLAIRE-1,3 DE DIAZOALCANES A DES ESTERS D'OXIMES
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Oximino-cyanacetic or malonesters 1, 2, 3 and 4 lead with diazoalcanes RCHN2 (R = H, CH3, Ph) to 1,2,3-triazolines.These triazolines present a low stability, however they are obtained crystallized with good yields.They are fully characterized and orientation of the cycloaddition is established.
- Perrocheau, J.,Carrie, R.
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p. 749 - 760
(2007/10/02)
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- N-Sulfonylamidines. Part IV. Intramolecular Cyclization of N-Sulfonylamidines of 2-Oxoacids: a new Synthesis of 3-Aminoisothiazole S,S-dioxides
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N-alkylsulfonylamides of α-ketoacids 3 bearing both a carbonyl group and at least one H-atom near to the SO2 group give easily an intramolecular ring-closure reaction by action of potassium t-butoxide producing the 3-amino-4,5-dihydro-4-hydroxy-isothiazol
- Clerici, Francesca,Marazzi, Guiseppe,Taglietti, Marcello
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p. 3227 - 3238
(2007/10/02)
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- COMPLEXES OF CYCLOMALTOHEPTAOSE WITH AROMATIC DIAZO COMPOUNDS: FORMATION AND REACTIONS
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Pyrolysis of the relatively stable, solid complexes of cyclomaltoheptaose (β-cyclodextrin) with phenyldiazomethane, 1-diazo-1-phenylethane, and diazo(diphenyl)methane results in degradation of the labile guests.The host matrix exerts "reaction-vessel" and "shape-selectivity" effects upon the reaction pathways of the guests and derivatives.The carbene insertion reaction with the β-cyclodextrin hydroxyl groups is regioselective.
- Abelt, Christopher J.,Lokey, Jonathan S.,Smith, Shelley H.
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p. 119 - 130
(2007/10/02)
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- THE SYNTHESIS OF ARYL DIAZOMETHANES
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A convenient and rapid method for preparing aryldiazomethanes from the related tosylhydrazones employing phase transfer catalysis with hydrocarbon solvents in good to excellent yields has been developed.
- Wulfman, David S.,Yousefian, Shahram,White, Jon M
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p. 2349 - 2352
(2007/10/02)
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- SYNTHESIS OF DERIVATIVES OF 3H-3-OXOPHENOTHIAZINE
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The synthesis of 8-carboxy-3H-3-oxophenothiazine and 8-carboxy-3-dimethyliminio-3H-phenothiazine chloride by the oxidation of 2-amino-4-carboxyphenyl 2-amino-5-hydroxyphenyl sulfide and 2-amino-4-carboxyphenyl 2-amino-5-dimethylaminophenyl sulfide with fe
- Varenikova, S. F.,Nekhoroshev, A. A.,Sevbo, D. P.,Ginzburg, O. F.
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p. 581 - 584
(2007/10/02)
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- 1,2,4,6-CYCLOHEPTATETRAENE: THE KEY INTERMEDIATE IN ARYLCARBENE INTERCONVERSIONS AND RELATED C7H6 REARRANGEMENTS
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Thermolysis or photolysis of phenyldiazomethane (2) produces phenylmethylene (3), which ring-expands to give 1,2,4,6-cycloheptatetraene (6).Spectroscopic and chemical evidence rule out bicyclo(4.1.0)hepta-2,4,6-triene (4), cycloheptatrienylidene (5), and bicyclo(3.2.0)hepta-1,3,6-triene (11) intermediates.The strained allene in cycloheptatetraene (6) exhibits infrared absorption at 1824 and 1816 cm-1.Deuterium substitution produces the expected 10-cm-1 shift in the allene absorption.Fluorine or chlorine substitution substantially enhances the allene absorption intensity.Deuterium labeling studies reveal that the intramolecular chemistry of cycloheptatetraene (6) involves reversible thermal or photochemical equilibriation with phenylmethylene (3).The intermolecular chemistry of 6 involves dimerization.At temperatures as low as 10 K, 6 forms a labile (2+2) dimer,7, which undergoes thermally allowed, electrocyclic ring opening to give heptafulvalene (8) upon warming to room temperature.The rearrangements of 7-acetoxynorbornadiene (9), 2-diazobicyclo(3.2.0)hepta-3,6-diene (31), and 8-diazobicyclo(2.2.2)octa-2,5-dien-7-one (33) all involve cycloheptatetraene (6) intermediates.
- McMahon, Robert J.,Abelt, Christopher J.,Chapman, Orville L.,Johnson, Jeffery W.,Kreil, Curits L.,et al.
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p. 2456 - 2469
(2007/10/02)
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- Synthesis and Properties of N2,3-Ethenoguanosine and N2,3-Ethenoguanosine 5'-Diphosphate
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N2,3-Ethenoguanosine has not been reported as a product of guanosine reaction with haloacetaldehydes.This is in contrast to the reaction of the ribosides yielding the well-known etheno compounds 1,N6-εAdo, 3,N4-εCyd, and 1,N2-εGuo.The base, N2,3-ethenoguanine was, however, synthesized, but not by direct reaction.We now report the synthesis of the nucleoside via reaction of O6-benzylguanosine with bromoacetaldehyde followed by hydrogenolytic debenzylation in the presence of palladium on charcoal.The structure of N2,3-ethenoguanosine was confirmed by NMR, UV, and FAB-MS data.The conformation of this nucleoside resembles that of guanosine, being predominantly in the anti form.The nucleoside was stable at neutrality, 37 deg C, but depurination was rapid at pH 1,24 deg C, with a t1/2 = 16 min.In contrast to 1,N2-εGuo, the angular N2,3-etheno derivatives are fluorescent, with the base having considerably higher fluorescence than the nucleoside.N2,3-Ethenoguanosine was converted to the 5'-diphosphate by conventional methods.This compound was a substrate for polynucleotide phosphorylase and could be copolymerized with CDP or ADP.There is little quench of the nucleotide fluorescence in copolymers.The recent report that N2,3-ethenoguanine is detected in chloroacetaldehyde-treated DNA after depurination makes N2,3-etheno modification of the guanine moiety of potential importance in understanding vinyl chloride induced carcinogenesis.
- Kusmierek, Jaroslaw T.,Jensen, David E.,Spengler, Sylvia J.,Stolarski, Ryszard,Singer, B.
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p. 2374 - 2378
(2007/10/02)
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- Building Units of Oligosaccharides, LXXXIII. - Synthesis of the Repeating Unit of the Teichuronic Acid of Micrococcus luteus
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The disaccharides β-D-ManNAcA-(1--->6)-D-Glc (27) and α-D-Glc-(1--->4)-D-ManNAcA (28) have been synthesized.They represent the repeating unit of the teichuronic acid of Micrococcus luteus.The key steps in the synthesis of the first disaccharide are format
- Paulsen, Hans,Helpap, Bernd,Lorentzen, Jens Peter
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p. 431 - 438
(2007/10/02)
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- Biosynthesis of Estrogens: Aromatization of (19R)-, (19S)-, and (19RS)--3β-Hydroxyandrost-5-en-17-ones by Human Placental Aromatase
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It is shown, with the use of (19R)- and (19S)--3β-hydroxyandrost-5-en-17-ones, that the "first" C-19 hydroxylation by human placental aromatase involves a normal kinetic isotope effect kH > kD >kT.The hydroxylation proceeds stereospecifically in the retention mode; i.e., the incoming hydroxyl assumes the orientation of the displaced (isotopic) hydrogen atom.
- Caspi, Eliahu,Arunachalam, Thangavel,Nelson, Peter A.
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p. 1847 - 1852
(2007/10/02)
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- Formation and Decomposition of 1,2,3-Triazolines Prepared from Diphenyl Phosphorazidate (DPPA) and Enamines of Diaryl-Type Ketones
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The pyrrolidine enamine 1 of deoxybenzoin reacted with diphenyl phosphorazidate (DPPA, (C6H5O)2P(O)N3) to give two amidines, the 1,2-migration product 7a and the 1,3-dipolar elimination product 8a in a ratio of 77:23.The reaction of DPPA with the enamine
- Kato, Nobuharu,Hamada, Yasumasa,Shioiri, Takayuki
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p. 2496 - 2502
(2007/10/02)
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- SYNTHESIS OF ACTINOMYCIN ANALOGS. XII. 4,6-DIACETYLAMINOCINNABARIC ACID AND ITS DERIVATIVES
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The selective reduction of methyl 2,4-dinitro-3-hydroxybenzoate gave methyl 2-nitro-3-hydroxy-4-aminobenzoate.The latter was used to synthesize 4,6-diacetylaminocinnabaric acid, its dimethyl ester, and the dihydrochloride of 4,6-diacetylaminocinnabaryl-bi
- Kolodkin, N. I.,Glibin, E. N.,Ginzburg, O. F.
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p. 1110 - 1115
(2007/10/02)
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- trans-2,3-Di-tert-butylthiirane 1,1-Dioxide and 2,5-Di-tert-butyl-2,5-dihydro-1,3,4-thiadiazole 1,1-Dioxides from tert-Butyldiazomethane and Sulfur Dioxide. Solvent Effects and Mechanisms of the Staudinger-Pfenninger-Reaction
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When allowed to react with sulfur dioxide tert-butyldiazomethane formed not only trans-di-tert-butylthiirane 1,1-dioxide (3) but also the diastereomeric 2,5-dihydro-1,3,4-thiadiazole 1,1-dioxides 7e which under base-catalysis rearranged to the 2,3-dihydro-1,3,4-thiadiazole 1,1-dioxide 11.The structures were deduced from IR, UV, and 1H-NMR-spectra, and from the products obtained after loss sulfur dioxide.Whereas increase of the solvent polarity favoured 3 over 7e, the diastereomer ratio cis-7e/trans-7e remained virtually unaffected.The ratio of thiirane 1,1-dioxide 3 to dihydrothiadiazole 1,1-dioxides did not depend on whether the intermediate tert-butylsulfene 6e had been generated from 5e and sulfur dioxide or from 2,2-dimethylpropane sulfonylchloride (14) and triethylamine.In contrast to reports in the literature, the reaction of the phenyldiazoalkanes 5f and 5h with sulfur dioxide afforded cis/trans ratios of the thiirane 1,1-dioxides 9f and 9h, respectively, which were only slightly influenced by the solvent.Apparently, the dihydrothiadiazole 1,1-dioxides 7 and hence their decomposition products, the azines 8 (as far as these do not arise from the direct decomposition of the diazo compounds), are the result of a cycloaddition between the diazoalkane 5 and the sulfene 6.In contrast, the thiirane 1,1-dioxides 9 seem to originate via the zwitterions 20 the formation of which is favoured over the cycloaddition by solvents of high polarity, by the presence of aryl substituents at the sulfene, as well as by the lack of alkyl groups.The dichotomy in the behaviour of sulfenes towards diazoalkanes can be traced back to the existence of two low-lying sulfene MO's, only one of which exhibits ?-symmetry.
- Quast, Helmut,Kees, Frieder
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p. 787 - 801
(2007/10/02)
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