- Reactions of α,β-enones with diazo compounds: Part 3. On the nature of the 1,5-ring closure of α,β-enone ylides
-
Carbonyl ylides arising from ethyl acetodiazoacetate/dimethyl diazomalonate and α,β-enones with mainly s-cis conformations underwent disrotatory cyclization to produce dihydrofuran derivatives. This process proved to be sensitive to steric effects. The corresponding ylides arising from rather s-trans α,β-enals yielded dioxole derivatives. The mechanisms of the reactions are discussed.
- Anac, Olcay,Oezdemir, Ayse Daut,Sezer, Oezkan
-
-
Read Online
- Asymmetric iridium(I)-catalyzed allylic alkylation of monosubstituted allylic substrates with phosphinooxazolines as ligands. isolation, characterization, and reactivity of chiral (allyl)iridium(III) complexes
-
IrI-catalyzed allylic alkylations of linear aryl-substituted allylic acetates proceed with enantiomeric excess of up to 95% ee using bidentate phosphinooxazolines as chiral ligands. The chiral (π-allyl)Ir III complexes 14 and 15 have
- Garcia-Yebra, Cristina,Janssen, Joerg P.,Rominger, Frank,Helmchen, Guenter
-
-
Read Online
- Traube's oxazomalonic acid is a 3-hydroxysydnone carboxylate with an E-ONNO geometry
-
An unusual heterocycle results from the Traube reaction of dimethyl malonate and nitric oxide (see scheme). This newly characterized E-ONNO sydnone is formed preferentially to the condensation product with a Z geometry.
- Arulsamy, Navamoney,Bohle, D. Scott
-
-
Read Online
- Polymer-mounted N3=P(MeNCH2CH2) 3N: A green, efficient and recyclable catalyst for room-temperature transesterifications and amidations of unactivated esters
-
Merrifield resin-supported N3P(MeNCH2CH 2)3N shows excellent activity in the transesterification of higher esters such as glyceryl tribenzoate to methyl esters. The catalyst was successfully cycled 20 times (albeit with an increase in reaction time) without compromising yield up to the 20th cycle. The catalyst also showed good performance in amidation reactions of unactivated esters with amino alcohols.
- Chintareddy, Venkat Reddy,Ho, Hung-An,Sadow, Aaron D.,Verkade, John G.
-
experimental part
p. 6523 - 6529
(2011/12/21)
-
- On the behaviour of dimethyl acetylenedicarboxylate in carbonylation and Khand reactions
-
Dimethyl acetylenedicarboxylate (DMAD) has been used as the alkyne component in the Khand reaction with norbornene under both thermal and N-oxide promoted conditions. Its thermolysis under CO pressure has also been reinvestigated and the structure of one
- Baxter, R. John,Knox, Graham R.,Pauson, Peter L.,Spicer, Mark D.
-
-
- Electrochemical oxidation of malonic esters in acetonitrile in the presence of iodides as mediators
-
Electrochemical oxidation of malonic esters in acetonitrile in the presence of iodides follows two different pathways depending on the nature of the cation. In the presence of LiI, alkyl 1,1,2,2,3,3-propanetetracarboxylates were obtained in 85-98% yields. In the presence of NaI, KI, or Bu4NI, the formation of 1,1,2,2-ethanetetracarboxylates and their subsequent dehydrogenation to ethenetetracarboxylates was the main reaction pathway.
- Fedukovich,Elinson,Nikishin
-
p. 599 - 602
(2007/10/03)
-
- Chemical and Electrochemical Oxidative Dimerization of Carbonyl Compounds by Cerium(IV) Salts. A Comparative Study
-
β-dicarbonyl and β-cyanocarbonyl compounds were dimerized chemically by CAN or by electrocatalysis using cerous nitrate as mediator.The saturated and unsaturated products of these oxidations are presented.
- Cho, Liu Yao,Romero, Jose Ricardo
-
p. 8757 - 8760
(2007/10/02)
-
- INVESTIGATION OF THE REACTION OF DIMETHYL DIAZOMALONATE WITH 1-PHENYLCYCLODODECENE IN THE PRESENCE OF COPPER(II) ACETYLACETONATE
-
Cu(AcAc)2 catalyzed reaction of dimethyl diazomalonate (dmdm) with 1-phenylcyclododecene was realized under different molar ratios and new compounds were obtained. The best procedures for synthesis of the addition products were noticed and the presence of a triploid-type carbenoid was claimed.
- Guenaydin, Keriman,Anac, Olcay
-
p. 1325 - 1330
(2007/10/03)
-
- Hydrogen Atoms as Convenient Synthetic Reagents: Mercury-Photosensitized Dimerization of Functionalized Organic Compounds in the Presence of H2
-
Hydrogen atoms are generated by mercury photosensitization in an unexceptional apparatus that makes them readily available for organic chemistry on a preparatively useful scale at 1 atm of pressure and temperatures from 0-150 °C. The H atoms add to CH2=CH-CH2X to give the intermediate radical CH3-(?CH)-CH2X, which dimerizes to give CH3CH(CH2X)-CH(CH2X)CH3. The saturated substrates CH3CH2CH2X undergo H abstraction to give CH3CH2(?CH)X as intermediates and CH3CH2CH(X)-CH(X)CH2CH3 as final products. The reaction shows a tolerance for different functional groups, X, which may be an alkyl or fluoroalkyl chain or contain vinyl, epoxy, ester, ketone, nitrile, and silyl groups. Radical disproportionation products are also formed but are easily separated. H atoms attack the weakest C-H bonds of the substrates with high selectivity. In our earliest direct mercury photosensitization, Hg* often failed to attack the substrate C-H bonds to give dimers; the presence of H2 strongly suppresses direct Hg* chemistry. H atoms are not sensitive to steric or polar effects Radical fragmentation is avoided by using "high" pressures (1 atm). Intramolecular radical additions to C=C bonds and methyl group 1,2-shift were also seen in some cases. Exceptional product ratios are observed for cross-reactions involving hydroxyalkyl radicals where H-bonding favors the homodimers in certain cases. Several bond strengths of C-H bonds α to CO were determined: EtCO2Me, 94.5; i-PrCO2Me, 92.7; cyclopentanone, 94.3; (i-Pr)2CO, 91.9 kcal/mol.
- Muedas, Cesar A.,Ferguson, Richard R.,Brown, Stephen H.,Crabtree, Robert H.
-
p. 2233 - 2242
(2007/10/02)
-
- Synthesis and characterization of metalated and cyclometalated platinum(II) and platinum (IV) complexes of β-diesters
-
The syntheses and characterization, via 1H and 13C NMR spectroscopy and X-ray crystallography, of several new C-malonato Pt(II) and Pt(IV) complexes are described. Cis acyclic bis complexes of C-metalated dimethyl malonate [e.g. Pt(phen)(C5H7O4)2], potential anti-tumor agents, were found to react with X2 and CuX2 (X = Cl, Br) to give the corresponding oxidized products but did not react with acyl halides or methyl vinyl ketone. Two new trans cyclometalated Pt(II) complexes, having 5- and 6-membered C,N-chelates, and a novel cyclometalated bridged acetate dimer were characterized by X-ray crystallography. C22H24N2O8Pt: a = 9.590 (2) ?, b = 29.594 (7) ?, c = 8.442 (2) ?, β = 106.02 (2)°, monoclinic, P21/c, Z = 4. C24H28N2O8Pt: a = 10.0905 (12) ?, b = 23.555 (2) ?, c = 10.823 (3) ?, β = 106.23 (2)°, monoclinic, P21/n, Z = 4. C26H30N2O12Pt2: a = 10.446 (5) ?, b = 16.669 (3) ?, c = 17.038 (3) ?, β = 97.19 (3)°, monoclinic, P21/n, Z = 4.
- Newkome, George R.,Theriot, Kevin J.,Fronczek, Frank R.,Villar, Bridgette
-
p. 2513 - 2523
(2008/10/08)
-
- DEHYDRODIMERIZATION OF KETONES, CARBOXYLIC ACIDS, AMIDES, ESTERS, ALCOHOLS, AND AMINES, VIA MERCURY-PHOTOSENSITIZATION
-
Selective dehydrodimerization of the title compounds can be carried out on a preparative scale at 1 atm. and at 25-110 deg C in a simple apparatus by Hg-photosensitized reaction under H2.
- Boojamra, Constantine G.,Crabtree, Robert H.,Ferguson, Richard R.,Muedas, Cesar A.
-
p. 5583 - 5586
(2007/10/02)
-
- Studies on fluoroalkylation and fluoroalkoxylation. Part 10. Electron-transfer induced reactions of perfluoroalkyl iodides and the dialkyl malonate anion and β-fragmentation of the halotetrafluoroethyl radical
-
Fluoroalkyl iodides, XCF2CF2I (X=F, perfluoroalkyl group) (1), react readily with malonic ester anion (2) in DMF to give {A figure is presented} (3), 1-hydroperfluoroalkane (4) and dimer of the anion (5). The reaction is accelerated by UV irradiation and partly suppressed by p-DNB. Diallyl ether (DAE) can trap the radical intermediates to afford five-membered ring products. Interestingly, in the case of 1 ( X = Cl, I ) the same reaction mainly yielded tetrafluoroethylene and 5 instead of 3 and 4. The radical intermediate XCF2CF·2 ( X=Cl ) can also be trapped by DAE to yield tetrahydrofuran derivatives. All these results can be rationalized in terms of the SRN1 mechanism.
- Chen, Qing-Yun,Qiu, Zai-Ming
-
p. 301 - 317
(2007/10/02)
-
- Cobalt-Mediated 1,4-Acylation/Alkylation of 1,3-Dienes
-
Acylcobalt complexes prepared from NaCo(CO)4 and organic halides reacted with butadiene, isoprene and allene to form (acyl-?-allyl)cobalt complexes.Reaction of these with stabilized carbanions resulted in alkylation at the unsubstituted ?-allyl terminus.The procedure provides an overall 1,4-acylation/alkylation of 1,3-dienes in which three carbon-carbon bonds are formed in a one-pot, four-step reaction sequence.
- Hegedus, Louis S.,Inoue, Yoshio
-
p. 4917 - 4921
(2007/10/02)
-