80515-60-2Relevant academic research and scientific papers
An unprecedented rearrangement in collision-induced mass spectrometric fragmentation of protonated benzylamines
Bialecki, Jason,Ruzicka, Josef,Attygalle, Athula B.
, p. 1195 - 1204 (2007/10/03)
The collision-induced dissociation (CID) mass spectra of several protonated benzylamines are described and mechanistically rationalized. Under collision-induced decomposition conditions, protonated dibenzylamine, for example, loses ammonia, thereby forming an ion of m/z 181. Deuterium labeling experiments confirmed that the additional proton transferred to the nitrogen atom during this loss of ammonia comes from the ortho positions of the phenyl rings and not from the benzylic methylene groups. A mechanism based on an initial elongation of a C-N bond at the charge center that eventually cleaves the C-N bond to form an ion/neutral complex of benzyl cation and benzylamine is proposed to rationalize the results. The complex then proceeds to dissociate in several different ways: (1) a direct dissociation to yield a benzyl cation observed at m/z 91; (2) an electrophilic attack by the benzyl cation within the complex on the phenyl ring of the benzylamine to remove a pair of electrons from the aromatic sextet to form an arenium ion, which either donates a ring proton (or deuteron when present) to the amino group forming a protonated amine, which undergoes a charge-driven heterolytic cleavage to eliminate ammonia (or benzylamine) forming a benzylbenzyl cation observed at m/z 181, or undergoes a charge-driven heterolytic cleavage to eliminate diphenylmethane and an immonium ion; and (3) a hydride abstraction from a methylene group of the neutral benzylamine to the benzylic cation to eliminate toluene and form a substituted immonium ion. Corresponding benzylamine and dibenzylamine losses observed in the spectra of protonated tribenzylamine and tetrabenzyl ammonium ion, respectively, indicate that the postulated mechanism can be widely applied. The postulated mechanisms enabled proper prediction of mass spectral fragments expected from protonated butenafine, an antifungal drug. Copyright
DEUTERIUM ISOTOPE EFFECTS IN THE META PHOTOCYCLOADDITION OF AROMATIC COMPOUNDS TO ALKENES
de Vaal, P.,Lodder, G.,Cornelisse, J.
, p. 4395 - 4398 (2007/10/02)
Secondary deuterium isotope effects were observed in the meta photocycloaddition of several aromatic compounds to cyclopentene.
Mechanism of the Reaction between Benzylmagnesium Chloride and Carbonyl Compounds. A Detailed Study with Formaldehyde
Benkeser, Robert A.,Snyder, Dudley C.
, p. 1243 - 1249 (2007/10/02)
The reaction of benzylmagnesium chloride in THF with monomeric formaldehyde has been studied in detail.A mechanism is presented which accounts for the formation of the products, 2-phenylethanol, o-tolylcarbinol, and o-(2-hydroxyethyl)benzyl alcohol.A change in technique for Grignard titration and formaldehyde addition results in a much-improved mass balance than achieved previously.The decreased yield of the major product, o-tolylcarbinol, with increased reaction time is explained in terms of a hitherto unsuspected equilibrium influenced by the polymerization of monomeric formaldehyde.An intermediate organometallic species which could lead to some of the diol product, o-(2-hydroxyethyl)benzyl alcohol can be trapped as the trimethylsilyl derivative, but the quantity is insufficient to account for the amount of diol when an excess of formaldehyde is employed.An ene or Prins reaction is invoked for the formation of most of the diol.Deuterium tracer studies suggest competition between a proton abstraction pathway leading to the trimethylsilyl-trapped organometallic species and a base-catalyzed, stereospecific 1,3 hydrogen shift.
