70975-44-9Relevant academic research and scientific papers
Silver-Catalysed Hydroarylation of Highly Substituted Styrenes
Dalton, Toryn,Gre?ies, Steffen,Das, Mowpriya,Niehues, Maximilian,Schrader, Malte L.,Gutheil, Christian,Ravoo, Bart Jan,Glorius, Frank
, p. 8537 - 8541 (2021/03/16)
Hydroarylation is an effective strategy to rapidly increase the complexity of organic structures by transforming flat alkene moieties into three-dimensional frameworks. Many strategies have already been developed to achieve the hydroarylation of styrenes,
Tautomerization of pyridine and 2-substituted pyridines to pyridylidene ligands by the iridium(I)-diene complex TpMe2Ir(η4- CH2=C(Me)C(Me)=CH2)
Vattier, Florencia,Salazar, Veronica,Paneque, Margarita,Poveda, Manuel L.,Alvarez, Eleuterio
, p. 498 - 510 (2014/02/14)
The complex TpMe2Ir(η4-CH2=C(Me)C(Me)= CH2) (3; TpMe2 = hydrotris(3,5-dimethylpyrazolyl)borate) reacts with pyridines NC5H4-2-R (R = H, Me, SiMe 3, F, OMe, NMe2, C(=O)Me) in cyclohexane, with formation of Ir(III) products whose natures depend strongly on the reaction conditions and on the R substituent. The simplest case is for R = NMe2, C(=O)Me, where κ2:σ2-but-2-enediyl N-H pyridylidenes, i.e. the result of the metal-promoted tautomerization of the pyridines, are the only species obtained from 60 to 150 C. For R = Me, F the N-bonded adducts TpMe2Ir(κ2-CH2C(Me)=C(Me)CH 2)(NC5H4-2-R) are formed at 60 C but, under harsher conditions (120-150 C), the observed products are, exclusively and respectively, the N-H pyridylidene and a bicyclic carbene compound derived from the formal, trans-stereospecific transfer of the N-H hydrogen of the corresponding (not observed) pyridylidene onto one of the carbons of the C=C double bond of the but-2-enediyl moiety, the other experiencing C-N formation. For R = OMe, the N adduct formed at 60 C transforms, at higher temperatures, into a mixture of the N-H pyridylidene and the bicyclic carbene, with no further evolution. More complex behavior is observed for the rest of the pyridines studied. Thus, when R = SiMe3, in addition to the expected N-H pyridylidene, two isomeric N-H pyridylidenes containing a κ2: σ2-but-1-enediyl coligand are also formed under kinetic control (60 C) but with both cleanly transforming into the former compound at higher temperatures. Finally, for R = H only the N adduct is formed under kinetic control at 25 C but this species transforms almost completely into a mixture of the N-H pyridylidene and two epimeric, N-C bicyclic carbenes after prolonged heating at 150 C. A detailed study of the temperature-dependent behavior of 3 in C6H6 has also been undertaken, revealing the interesting deuteration of its =CH2 termini by C6D6.
A general and stereoselective method for synthesis of tri- and tetrasubstituted alkenes
Macia?giewicz,Dybowski,Skowrońska
, p. 6057 - 6066 (2007/10/03)
A convenient, general and stereoselective synthesis of trisubstituted alkenes and tetrasubstituted alkenes containing a cyanide function as well as trisubstituted episulphides have been elaborated. Methodology described for the preparation of these compounds is based on the corresponding readily available selenophosphates 1 and thiophosphates 2.
Radical-Stabilization-Energy - the MMEVBH Force Field
Roth, Wolfgang R.,Staemmler, Volker,Neumann, Martin,Schmuck, Carsten
, p. 1061 - 1118 (2007/10/02)
Making use of the VB method of Malrieu et al. a force field has been developed, which allows to calculate heats of formation of hydrocarbons (conjugated and non-conjugated olefins, radicals and diradicals) with high accuracy.With this method radical stabilization energies (RSE) for a great number of delocalized radicals are calculated and compared with experimental values, derived from shock-tube measurements of dissociation energies or from rotational barriers of substituted olefins.A detailed analysis of the RSE with respect to structure, substituents, strain, and aromaticity is presented. - Key Words: Resonance energy / Heats of formation / Single pulse shock tube / Intrisic rotational barrier
Radical ions in photochemistry. 21. The photosensitized (electron transfer) tautomerization of alkenes; the phenyl alkene system
Arnold, Donald R.,Mines, Shelley A.
, p. 689 - 698 (2007/10/02)
Alkenes, conjugated with a phenyl group, can be converted to nonconjugated tautomers by sensitized (electron transfer) irradiation.For example, irradiation of an acetonitrile solution of the conjugated alkene 1-phenylpropene, the electron accepting photosensitizer 1,4-dicyanobenzene, the cosensitizer biphenyl, and the base 2,4,6-trimethylpiridine gave the nonconjugated tautomer 3-phenylpropene in good yield.Similarly, 2-methyl-1-phenylpropene gave 2-methyl-3-phenylpropene, and 1-phenyl-1-butene gave E- and Z-1-phenyl-2-butene.The reaction also works well with cyclic alkenes.For example, 1-phenylcyclohexene gave 3-phenylcyclohexene, and 1-(phenylmethylene)cyclohexane gave 1-(phenylmethyl)cyclohexene.The proposed mechanism involves the initial formation of the alkene radical cation and the sensitizer radical anion, induced by irradiation of the sensitizer and mediated by the cosensitizer.Deprotonation of the radical cation assisted by the base gives the ambident radical, which is then reduced to the anion by the sensitizer radical anion.Protonation of the ambident anion at the benzylic position completes the sequence.Reprotonation at the original position is an energy wasting step.Tautomerization is driven toward the isomer with the higher oxidation potential, which is, in the cases studied, the less thermodinamically stable isomer.The tautomerization of 2-methyl-1-phenylbutene gave both 2-phenylmethyl-1-butene and 2-methyl-1-phenyl-2-butene (E and Z isomers), while 2,3-dimethyl-1-phenylbutene gave only 3-methyl-2-phenylmethyl-1-butene.In the latter case, steric interaction of the methyls on the isopropyl group prevents effective overlap of the tertiary carbon-hydrogen bond with the singly occupied molecular orbital, thus inhibiting deprotonation from this site.Key words: photosensitized, electron transfer, alkene, tautomerization, radical cation.
