79449-94-8Relevant academic research and scientific papers
Regarding the Mechanism of the Carbonyl-Forming Elimination Reaction of Alkyl Nitrates
Kwart, H.,George, T. J.,Horgan, A. G.,Lin, Y. T.
, p. 5143 - 5147 (1981)
The temperature dependence of kH/kD for the formation of benzaldehyde through base-catalyzed HNO2 elimination from benzyl nitrate is indicative of a tunneling pathway of linear proton transfer.The same criterion applied to the uncatalyzed, gas-phase reaction reveals a cyclic transition state of nonlinear proton transfer.From these and other considerations it has been deduced that the base-catalyzed reaction is best formulated as a cyclic process of linear H transfer and is consistent with an ECO1cb rather than the ECO2 mechanism previously claimed.
An Iron-Mesoionic Carbene Complex for Catalytic Intramolecular C-H Amination Utilizing Organic Azides
Albrecht, Martin,Keilwerth, Martin,Meyer, Karsten,Pividori, Daniel M.,Stroek, Wowa
, p. 20157 - 20165 (2021/12/09)
The synthesis of N-heterocycles is of paramount importance for the pharmaceutical industry. They are often synthesized through atom economic and environmentally unfriendly methods, generating significant waste. A less explored, but greener, alternative is
Catalytic C-H Amination Mediated by Dipyrrin Cobalt Imidos
Baek, Yunjung,Betley, Theodore A.
, p. 7797 - 7806 (2019/05/22)
Reduction of (ArL)CoIIBr (ArL = 5-mesityl-1,9-(2,4,6-Ph3C6H2)dipyrrin) with potassium graphite afforded the novel CoI synthon (ArL)CoI. Treatment of (ArL)CoI with a stoichiometric amount of various alkyl azides (N3R) furnished three-coordinate CoIII alkyl imidos (ArL)Co(NR), as confirmed by single-crystal X-ray diffraction (R: CMe2Bu, CMe2(CH2)2CHMe2). The exclusive formation of four-coordinate cobalt tetrazido complexes (ArL)Co(κ2-N4R2) was observed upon addition of excess azide, inhibiting any subsequent C-H amination. However, when a weak C-H bond is appended to the imido moiety, as in the case of (4-azido-4-methylpentyl)benzene, intramolecular C-H amination kinetically outcompetes formation of the corresponding tetrazene species to generate 2,2-dimethyl-5-phenylpyrrolidine in a catalytic fashion without requiring product sequestration. The imido (ArL)Co(NAd) exists in equilibrium in the presence of pyridine with a four-coordinate cobalt imido (ArL)Co(NAd)(py) (Ka = 8.04 M-1), as determined by 1H NMR titration experiments. Kinetic studies revealed that pyridine binding slows down the formation of the tetrazido complex by blocking azide coordination to the CoIII imido. Further, (ArL)Co(NR)(py) displays enhanced C-H amination reactivity compared to that of the pyridine-free complex, enabling higher catalytic turnover numbers under milder conditions. The mechanism of C-H amination was probed via kinetic isotope effect experiments [kH/kD = 10.2(9)] and initial rate analysis with para-substituted azides, suggesting a two-step radical pathway. Lastly, the enhanced reactivity of (ArL)Co(NR)(py) can be correlated to a higher spin-state population, resulting in a decreased crystal field due to a geometry change upon pyridine coordination.
Ene Reaction of Arylallyl Alkenes with C60. A Mechanistic Approach
Chronakis, Nikos,Orfanopoulos, Michael
, p. 1909 - 1912 (2008/02/11)
(Matrix Presented) The ene reaction of arylallyl alkenes with C60 occurs either by a concerted mechanism or by the reversible formation of a charged or a dipolar intermediate, followed by the C-H(D) breakage in a rate-limiting step.
UNUSUAL DOWNFIELD DEUTERIUM ISOTOPE SHIFT EFFECT ON THE 31P CHEMICAL SHIFTS OF DIALKYL BENZYLPHOSPHONATES
Lee, Sueg-Geun,Bentrude, Wesley G.
, p. 219 - 222 (2007/10/02)
A surprising linear downfield effect on the 31P chemical shift of a benzylphosphonate of deuterium substitution on the bezyl carbon has been noted.Its potential usefulness in mechanistic studies is suggested.
Side Chain Hydroxylation of Aromatic Hydrocarbons by Fungi. Part 2. Isotope Effects and Mechanism
Holland, Herbert L.,Brown, Frances M.,Munoz, Benito,Ninnis, Ronald W.
, p. 1557 - 1564 (2007/10/02)
The benzylic hydroxylation of ethylbenzene, p-diethylbenzene, tetralin, indane, and toluene by the fungi Mortierella isabellina, Cunninghamella echinulata, and Helminthosporium species has been investigated by the use of deuterium-labelled substrates.An i
Primary and Secondary Kinetic Deuterium Isotope Effects and Transition-State Structures for Benzylic Chlorination and Bromination of Toluene
Hanzlik, Robert P.,Schaefer, Angela R.,Moon, Joseph B.,Judson, Charles M.
, p. 4926 - 4930 (2007/10/02)
As a chemical model for benzylic hydroxylations effected by cytochrome P-450 enzymes, the chlorination of PhCH3, PhCH2D, PhCHD2, and PhCD3 in a two-phase system of hypochlorite/CH2Cl2 with a phase-transfer catalyst has been investigated.On the basis of th
Intramolecular Kinetic Deuterium Isotope Effects on Microsomal Hydroxylation and Chemical Chlorination of Toluene-α-d1 and Toluene-α,α-d2
Hanzlik, Robert P.,Hogberg, Kerstin,Moon, Joseph B.,Judson, Charles M.
, p. 7164 - 7167 (2007/10/02)
Deuterated toluenes PhCH2D and PhCHD2 were synthesized and subjected separately to microsomal hydroxylation in vitro.Mass spectral analysis of the resulting benzyl alcohols indicated substatial excess retention of deuterium, a consequence of the combined
Bromide Ion Promoted β-Elimination in α-Bromo Ester Substrates. Evidence for an Intermediate in the E2C Reaction
Kwart, Harold,Gaffney, Anne
, p. 4502 - 4508 (2007/10/02)
The TDKIE criteria of transition state geometry in H-transfer reactions have been applied in the title reactions; a bent transition state consistent with the geometry of the E2C reaction has been verified by the results of intramolecular and intermolecular competition modes of determining kH/kD as a function of temperature.The extraordinary magnitude measured for the α secondary deuterium isotope effect in the E2C mechanism is reconciled with a very loose transition state and an acute angle of H-abstraction in the course of rearward approach to Cα by the promoter base.The virtual identity of the inter- and intramolecular isotope effects can be correlated by the assumption of a reaction intermediate of trigonal-bipyramid structure surrounding Cα and in which the abstractable H and D atoms are equally available to the action of the promoter base.The properties of this intermediate (4), by way of contrast with the transition state of an SN2 process, are discussed in detail.
Effect of Dimethyl Sulfoxide Solvent in the Thermolysis of Alkyl Nitrates Elucidated by the Temperature Dependence of a Kinetic Isotope Effect
Kwart, H.,Brechbiel, M. W.
, p. 461 - 463 (2007/10/02)
The cyclic, bent TS* of gas-phase thermolytic decomposition of benzyl nitrate has been compared to the analogous thermal elimination of amine oxides in diglyme solution.The use of Me2SO solvent in amine oxide thermolysis has been shown to alter the TS* to one which accommodates linear H transfer.Me2SO solvent in the case of benzyl nitrate is now found to afford a nearly quantitative conversion to benzaldehyde.Other alkyl nitrates show a similarly facile reaction to produce good yields of the carbonyl product.However, through measurement of the temperature dependence of kH/kD with benzyl-α-d nitrate it is found that the TS* for decomposition is little altered by comparison with the gas-phase thermolysis reaction.The differences in behavior of the amine oxide and alkyl nitrate reactions in Me2SO and the possible origins of these differences are discussed briefly.
