68922-87-2Relevant articles and documents
When cobalt-mediated [2 + 2 + 2] cycloaddition reaction dares go astray: Synthesis of unprecedented cobalt(III)-complexes
Delorme, Marion,Punter, Alexander,Oliveira, Raquel,Aubert, Corinne,Carissan, Yannick,Parrain, Jean-Luc,Amatore, Muriel,Nava, Paola,Commeiras, Laurent
supporting information, p. 15767 - 15771 (2019/11/11)
In sharp contrast with the standard [2 + 2 + 2] cycloaddition reaction of diyne/ene, cobalt-mediated cycloadditions with γ-alkylidenebutenolide led to unprecedented cobalt(iii) polycyclic complexes. A plausible mechanism supported by a computational study based on an unusual fragmentation of the butenolide moiety was postulated to account for this original reaction.
Iron-catalyzed, hydrogen-mediated reductive cyclization of 1,6-enynes and diynes: Evidence for bis(imino)pyridine ligand participation
Sylvester, Kevin T.,Chirik, Paul J.
supporting information; experimental part, p. 8772 - 8774 (2009/12/04)
(Chemical Equation Presented) The bis(imino)pyridine iron dinitrogen complex (iPrPDI)Fe(N2)2 catalyzes the hydrogen-mediated reductive cyclization of enynes and diynes with turnover frequencies comparable to those of established precious metal catalysts. Amino, oxygenated, and carbon-based substrates are readily cyclized to the corresponding hetero- and carbocycles with 5 mol % iron and 4 atm H2 at 23°C. Stoichiometric reactions between selected substrates and the iron compound under a N2 atmosphere established transfer dehydrogenation from an isopropyl aryl substituent to either the enyne or diyne substrate. In situ monitoring of the catalytic reaction by 1H NMR spectroscopy coupled with deuterium labeling experiments established rapid cyclization followed by turnoverlimiting hydrogenation. Copyright
NOVEL 3, 4-PROPYLENEDIOXYTHIOPHENE DERIVATIVES WITH PENDANT FUNCTIONAL GROUPS
-
Page/Page column 6, (2010/11/24)
The present invention relates to the syntheses of 3,4-propylenedioxythiophenes of the formula (I) wherein R represents a n-valent linear or branched, optionally substituted, aliphatic C1-Cn radical and Y represents a pendant functional group. Further, methods for the preparation of the said compounds are disclosed.
Substituent Effects on the C-C Bond Strength, 19. Geminal Substituent Effects, 10. Radical Stabilization Enthalpies of α,α-Bis(methoxycarbonyl)alkyl and Tris(methoxycarbonyl)methyl Radicals
Rakus, Klaus,Verevkin, Sergey P.,Keller, Manfred,Beckhaus, Hans-Dieter,Ruechardt, Christoph
, p. 1483 - 1494 (2007/10/02)
Heats of formation ΔH0f(g) were determined from enthalpies of combustion ΔH0f(c) and enthalpies of vaporization ΔH0vap or sublimation ΔH0sub for the eight substituted methanetricarboxylates 2a-h.From these data and from previously determined enthalpies of formation ΔH0f of substituted malonic esters new thermochemical group increments were derived.From these increments and from the recently published improved increments for carboxylic acid esters the gem. interaction enthalpies of two and three COOR groups were calculated.The radical stabilization enthalpies RSE of α,α-bis(methoxycarbonyl)alkyl (18.2 kJ mol-1, 1a) and tris(methoxycarbonyl)methyl radicals (5.2 kJ mol-1, 1b) were derived from kinetic data obtained by means of our previously developed protocol.They were corrected for the gem. interaction energies of the ester groups in the ground state and are satisfactorily explained by an additive stabilizing effect for the ester substituents and by dipolar substituent interactions in the radicals.The dipolar energies were taken from MM2 calculations. - Keywords: Enthalpies of formation / Geminal substituents, energetic interaction of / Bond cleavage, C-C, kinetics of / Radicals, stabilization of / Increments, thermochemical, of esters
