71258-22-5Relevant academic research and scientific papers
Identification and biosynthesis of tropone derivatives and sulfur volatiles produced by bacteria of the marine Roseobacter clade
Thiel, Verena,Brinkhoff, Thorsten,Dickschat, Jeroen S.,Wickel, Susanne,Grunenberg, Joerg,Wagner-Doebler, Irene,Simon, Meinhard,Schulz, Stefan
experimental part, p. 234 - 246 (2010/04/29)
Bacteria of the Roseobacter clade are abundant marine bacteria and are important contributors to the global sulfur cycle. The volatiles produced by two of its members, Phaeobacter gallaeciensis and Oceanibulbus indolifex, were analyzed to investigate whether the released compounds are derived from sulfur metabolism, and which biosynthetic pathways are involved in their formation. Both bacteria emitted different sulfides and thioesters, including new natural compounds such as 5-methyl phenylethanethioate (16) and butyl methanesulfonate (21). The S-methyl alkanoates were identified by comparison with standards that were synthesized from the respective methyl alkanoates by a new method using an easily prepared aluminium/sulfur reagent. Phaeobacter gallaeciensis is also able to produce tropone (37) in large amounts. Its biosynthesis was investigated by various feeding experiments, showing that 37 is formed via a deviation of the phenylacetate catabolism. The unstable tropone hydrate 42 was identified as an intermediate of the tropone biosynthesis that was also released together with tropolone (38). The Royal Society of Chemistry 2010.
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
The remarkable electron impact mass spectrum of (2-benzyl-1,3-xylylene)-15- crown-4: Expulsion of triethylene glycol by double hydrogen transfer
Gruter, Gert-Jan M.,Van Baar, Ben L. M.,Gerrits, Tom J.,Akkerman, Otto S.,Bickelhaupt, Friedrich,Barkow, Anja,Kuck, Dietmar
, p. 925 - 932 (2007/10/03)
During our investigations of the synthesis of magnesium-containing crown ethers, the mass spectral characterisation of a precursor, (2-benzyl-1,3- xylylene)-15-crown-4 (C21H26O4), leads to a surprising result: its electron
Mechanism of the reaction of methylene with benzene: A study of kinetic hydrogen isotope effects and theoretical calculations
Hartz, Nikolai,Surya Prakash,Olah, George A.
, p. 901 - 905 (2007/10/02)
The reaction mechanism of singlet and triplet methylene with benzene and related aromatic compounds was investigated by kinetic isotope effects (KIEs), solvent effects, and product studies. The results are further rationalized by a series of ab initio calculations at MP2/6-31G*//RHF/6-31G* and UMP2/6-31G*//UHF/6-31G* levels of theory. The proposed 1c intermediate for the triplet reaction was found by means of the calculations, whereas no singlet analog 1 could be found.
Generation and IR spectroscopic study of benzyl radical
Baskir, E. G.,Maltsev, A. K.,Korolev, V. A.,Khabashesku, V. N.,Nefedov, O. M.
, p. 1438 - 1440 (2007/10/02)
The benzyl radical C6H5CH2 has been obtained by gas phase pyrolysis of two different precursors, benzyl bromide and dibenzyl, and studied in an argon matrix at 12 K by IR spectroscopy.Similarly, the deuterosubstituted benzyl radicals, C6H5CD2 and C6D5CH2,
Isotopic selectivity in the one-electron-promoted cleavage of ring-deuterated naphthylmethyl phenyl ethers and naphthyl benzyl ethers
Guthrie, Robert D.,Shi, Buchang
, p. 3136 - 3139 (2007/10/02)
(1-Naphthyl)methyl phenyl ether (1) and 1-naphthyl benzyl ether (2) have been allowed to compete against isotopically modified 1 or 2 in reactions with fluoranthene radical anion, F?-, and biphenyl radical anion, B?-. These reactions involve electron transfer followed by CH2-O bond cleavage. Discrimination is observed in favor of 1 when it competes with naphthalene-ring-deuterated 1 (C10D7CH2OC6H5) in reaction with F?-. Discrimination is not observed when the naphthalene ring of 2 is modified. Neither naphthalene-ring-deuterated 1 nor 2 showed isotopic selectivity in reaction with B?-. Small but experimentally significant discriminations are detected for the case of 2 with modified benzyl groups (C6D5CH2 and C6D5CD2) reacting with F?-. The results are interpreted as indicating a transition state for cleavage of 1?- in which the extra electron is substantially located in the π* molecular orbital of the naphthalene ring. Cleavage of 2?- is better viewed as involving a σ*-like transition state.
Skeletal Rearrangements on Chemical Ionization of Dibenzyl Ether and Derivatives
Kingston, Eric E.,Shannon, James S.,Diakiw, Vladimir,Lacey, Michael J.
, p. 428 - 440 (2007/10/02)
Protonated molecular ions of dibenzyl ether, formed by chemical ionization using hydrogen and isobutane as reagent gases, undergo skeletal rearrangements to lose water and formaldehyde, both in the ion source and the flight path.The rearrangements have been elucidated by deuterium labelling and chemical substitution.The water lost contains the reagent proton and an aromatic hydrogen atom, and the aromatic hydrogen atoms have been shown to be mobile prior to the reaction.It is proposed that the skeletal rearrangement for water loss is initiated by protonation on the other oxygen atom, followed by benzyl migration.The formaldehyde loss contains benzylic hydrogen atoms exclusively, and it is proposed that the skeletal rearrangement is preceded by hydrogen rearrangement of an oxygen protonated molecular ion to a ring protonated molecular ion.Daughter ion structures are supported by comparisons of their collision induced dissociation spectra with those of isomeric ions prepared by alternative routes.
