Vinyl anion synthesis in the gas phase

Anderson, Kraig K.; Kass, Steven R.

doi:10.1016/s0040-4039(00)99398-5

Cited by 12 publications

(9 citation statements)

References 16 publications

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“…We have recently developed a Fourier transform mass spectrometry (FTMS) method, building upon earlier work in the flowing afterglow, for the bracketing of less acidic sites in molecules that have multiple acidic sites; the experimental procedure has been described previously [14,[65][66][67][68][69][70][71][72][73][74][75][76][77][78]. Briefly, using uracil as an example, when hydroxide is used to deprotonate uracil, two ions are formed, the N1-deprotonated uracil and the N3-deprotonated uracil.…”

Section: Methodsmentioning

confidence: 99%

The acidity of uracil and uracil analogs in the gas phase: Four surprisingly acidic sites and biological implications

Kurinovich

Lee

2002

J. Am. Soc. Mass Spectrom.

160

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The gas phase acidities of a series of uracil derivatives (1-methyluracil, 3-methyluracil, 6-methyluracil, 5,6-dimethyluracil, and 1,3-dimethyluracil) have been bracketed to provide an understanding of the intrinsic reactivity of uracil. The experiments indicate that in the gas phase, uracil has four sites more acidic than water. Among the uracil analogs, the N1-H sites have ⌬H acid values of 331-333 kcal mol Ϫ1 ; the acidity of the N3 sites fall between 347-352 kcal mol Ϫ1 . The vinylic C6 in 1-methyluracil and 3-methyluracil brackets to 363 kcal mol Ϫ1 , and 369 kcal mol Ϫ1 in 1,3-dimethyluracil; the C5 of 1,3-dimethyluracil brackets to 384 kcal mol Ϫ1 . Calculations conducted at B3LYP/6-31ϩG* are in agreement with the experimental values. The bracketing of several of these sites involved utilization of an FTMS protocol to measure the less acidic site in a molecule that has more than one acidic site, establishing the generality of this method. In molecules with multiple acidic sites, only the two most acidic sites were bracketable, which is attributable to a kinetic effect. The measured acidities are in direct contrast to in solution, where the two most acidic sites of uracil (N1 and N3) are indifferentiable. The vinylic C6 site is also particularly acidic, compared to acrolein and pyridine. The biological implications of these results, particularly with respect to enzymes for which uracil is a substrate, are discussed. (J Am Soc Mass Spectrom 2002, 13, 985-995)

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Section: Methodsmentioning

confidence: 99%

The acidity of uracil and uracil analogs in the gas phase: Four surprisingly acidic sites and biological implications

Kurinovich

Lee

2002

J. Am. Soc. Mass Spectrom.

160

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show abstract

Section: Methodsmentioning

confidence: 99%

“…We have recently developed an FTMS method, building upon earlier work in the flowing afterglow, for the bracketing of less acidic sites in molecules that have multiple acidic sites; the experimental procedure and limitations have been described previously. 14,32,[35][36][37][38][39][40][41][42][43][44][45][46][47][48] Throughout the text, the term "gas-phase acidity" is used to refer to the enthalpic (∆H) change associated with deprotonation.…”

Section: Methodsmentioning

confidence: 99%

Acidity of Adenine and Adenine Derivatives and Biological Implications. A Computational and Experimental Gas-Phase Study

2002

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The gas-phase acidities of adenine, 9-ethyladenine, and 3-methyladenine have been investigated for the first time, using computational and experimental methods to provide an understanding of the intrinsic reactivity of adenine. Adenine is found to have two acidic sites, with the N9 site being 19 kcal mol(-1) more acidic than the N10 site; the bracketed acidities are 333 +/- 2 and 352 +/- 4 kcal mol(-1), respectively. Because measurement of the less acidic site can be problematic, we benchmarked the adenine N10 measurement by bracketing the acidity of 9-ethyladenine, which has the N9 site blocked and allows for exclusive measurement of the N10 site. The acidity of 9-ethyladenine brackets to 352 +/- 4 kcal mol(-1), comparable to that of the N10 site of the parent adenine. Calculations and experiments with 3-methyladenine, a harmful mutagenic nucleobase, uncovered the surprising result that the most commonly written tautomer of 3-methyladenine is not the most stable in the gas phase. We have found that the most stable tautomer is the "N10 tautomer" 10, as opposed to the imine tautomer 3. The bracketed acidity of 10 is 347 +/- 4 kcal mol(-1). Since 10 is not a viable species in DNA, 3 is a likely tautomer; calculations indicate that this form has an extremely high acidity (320-323 kcal mol(-1)). The biological implications of these results, particularly with respect to enzymes that cleave alkylated bases from DNA, are discussed.

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“…Hundreds of diazirine derivatives have been prepared, and many serve as stable precursors for carbenes . In addition, the diazirine moiety has been incorporated in biologically active compounds to function as photoaffinity reagents for receptors and as hydrophobic reagents for membrane organization studies. − Diazirines also enjoy a rich chemistry in the gas phase as precursors for vinyl anions, heterocyclic 4π electron systems, carbynes, and hydrazyl anions …”

Section: Introductionmentioning

confidence: 99%

Benzocyclobutadienyl Anion: Formation and Energetics of an Antiaromatic Molecule

Broadus

Kass

2000

J. Org. Chem.

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Benzocyclobutadienyl diazirine (2) was synthesized and reacted with hydroxide ion in a Fourier transform mass spectrometer to afford the conjugate base of benzocyclobutadiene (1a). Authentication of the ion structure was carried out by a derivatization experiment (i.e., la was converted to benzocyclobutenone enolate, which has previously been studied), and its reactivity was explored. Thermochemical data for benzocyclobutadiene (1) were obtained (deltaH(o)acid (1) = 386 +/- 3 kcal mol(-1), EA(1r) = 1.8 +/- 0.1 eV, and C-H BDE (1) = 114 +/- 4 kcal mol(-1)), compared to MP2 and B3LYP calculations, and contrasted to a series of model compounds. Cyclobutadienyl radical appears to be quite different from benzocyclobutadienyl radical (1r) and worth further exploration.

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Vinyl anion synthesis in the gas phase

Cited by 12 publications

References 16 publications

The acidity of uracil and uracil analogs in the gas phase: Four surprisingly acidic sites and biological implications

The acidity of uracil and uracil analogs in the gas phase: Four surprisingly acidic sites and biological implications

Acidity of Adenine and Adenine Derivatives and Biological Implications. A Computational and Experimental Gas-Phase Study

Benzocyclobutadienyl Anion: Formation and Energetics of an Antiaromatic Molecule

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