5161-49-9Relevant academic research and scientific papers
Nucleophilic intermolecular chemistry and reactivity of dimethylcarbene
Cang, Hui,Moss, Robert A.,Krogh-Jespersen, Karsten
, p. 2730 - 2737 (2015/03/04)
Experimental and computational studies find that dimethylcarbene (DMC), the parent dialkylcarbene, is both predicted to be and functions as a very reactive nucleophilic carbene in addition reactions with five simple alkenes. Activation energies and enthal
Rearrangement of dimethylcarbene to propene: Study by laser flash photolysis and ab initio molecular orbital theory
Ford, Francis,Yuzawa, Tetsuro,Platz, Matthew S.,Matzinger, Stephan,Fülscher, Markus
, p. 4430 - 4438 (2007/10/03)
Laser flash photolysis (Nd:YAG laser, 355 nm, 35 mJ, 150 ps) of dimethyldiazirine and dimethyldiazirine-d6 produces dimethylcarbene (DMC) and dimethylcarbene-d6 (DMC-d6), respectively. The carbenes were trapped with pyridine to form ylides which absorb around 364 nm. It was possible to resolve the growth of the ylides as a function of pyridine concentration in Freon-113, α, α,α-trifluoromethylbenzene, and perfluorohexane as a function of temperature. The observed rate constant (k(obs)) of ylide formation was linearly dependent on the concentration of pyridine in all solvents and at all temperatures. From plots of kobs versus [pyridine] it was possible to extract values of k(pyr) (the absolute rate constant of reaction of the carbene with pyridine) and τ, the carbene lifetime in the absence of pyridine, and their associated Arrhenius parameters. In Freon-113 and α, α, α-trifluoromethylbenzene the carbenes decay both by rearrangement and by reaction with solvent. In perfluorohexane the carbene decay appears to be predominantly unimolecular. The experimental results are compared with ab initio molecular orbital calculations. The experimentally determined barrier to disappearance of DMC in perfluorohexane (2.56 ± 0.05 kcal/mol) is much smaller than that calculated (7.4 ± 2 kcal/mol) using ab initio molecular orbital theory. The Arrhenius parameters and isotope effects indicate that the rearrangement of DMC in perfluorohexane has a large component of quantum mechanical tunneling. The activation energy for the disappearance of DMC-d6 in perfluorohexane (5.63 ± 0.03 kcal/mol) is consistent with calculations which indicate that QMT makes only a minor contribution to the deuterated system under the conditions of this study.
ONE-STEP SYNTHESIS OF DIAZIRINES FROM O-TOSYL KETOXIMES AND ALKOXYAMINES
Shustov, G. V.,Tavakalyan, N. B.,Pleshkova, A. P.,Kostyanovskii, R. G.
, p. 600 - 605 (2007/10/02)
The reaction of O-tosyloximes of acetone, hexafluoroacetone, and mesoxalic acid esters with alkoxyamines leads to the corresponding diazirines, while the reaction of benzophenone O-tosyloxime with methoxyamine gives only benzophenone O-methyloxime.O-Esters of acetoxime were isolated along with 3,3-dimethylazirine also in the reaction of O-tosylacetoxime with alkoxyamines.Nucleophilic attack of alkoxyamines on O-tosyloximes of mesoxalates is realized at the carbon atom of not only the C=O bond but also at the carbon atom of the C=O bond, and the latter leads to fragmentation of the O-tosyloxime to give N-alkoxycarbamates, a cyanocarbonate ester, and p-toluenesulfonic acid.In the presence of triethylamine, which blocks the C=N bond, the reaction of mesoxalate O-tosyloxime proceeds only via the fragmentation pathway.The mechanism of the formation of diazirines in the reaction of O-tosylketoximes with alkoxyamines is discussed.
