Organic mass spectrometry—V

Goto, Toshio; Tatematsu, Akira; Hata, Yoshiteru; Muneyuki, Ryonosuke; Tanida, Hiroshi; Tori, K.

doi:10.1016/s0040-4020(01)82142-6

Cited by 36 publications

(10 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The position of molecular ion (M R ) corresponds to the sum of molecular masses of the substrates 1 i 2a (m/e ¼ 260), which in combination with the results of elemental analysis (CHN), allow us to assign the formula C 13 H 12 N 2 O 4 to the isolated cycloadducts. The fragmentation pattern of M R. is a combination of the fragmentation patterns characteristic of norbornenes [30][31][32] and nitrocycloalkanes, [33][34][35] but it does not allow differentiation between the stereoisomers. However, the stereochemistry assignment was possible with the aid of 1 H-NMR spectroscopy.…”

Section: Stereospecificity Of the Reaction Of Cyclopentadiene With E-mentioning

confidence: 99%

Stereoselectivity and kinetics of [4 + 2] cycloaddition reaction of cyclopentadiene to para‐substituted E‐2‐arylnitroethenes

Jasiński¹,

Kwiatkowska²,

Barański³

2011

J of Physical Organic Chem

View full text Add to dashboard Cite

In spite of diversified electrophilicity of E‐2‐arylnitroethenes, their [4 + 2] cycloaddition reactions with cyclopentadiene leads to the corresponding 6‐endo‐aryl‐5‐exo‐nitronorbornenes and 6‐exo‐aryl‐5‐endo‐nitronorbornenes as the only reaction products. Stereoselectivity, substituent and solvent effects, and activation parameters, suggest that these reactions occur via a synchronous concerted mechanism on both competing pathways. The experimental results obtained are consistent with the data from B3LYP/6‐31G(d) calculations. Due to high electrophilicity of E‐2‐arylnitroethenes, the reactions studied should be considered as polar [4 + 2] cycloadditions. Copyright © 2011 John Wiley & Sons, Ltd.

show abstract

Section: Stereospecificity Of the Reaction Of Cyclopentadiene With E-mentioning

confidence: 99%

Stereoselectivity and kinetics of [4 + 2] cycloaddition reaction of cyclopentadiene to para‐substituted E‐2‐arylnitroethenes

Jasiński¹,

Kwiatkowska²,

Barański³

2011

J of Physical Organic Chem

View full text Add to dashboard Cite

show abstract

“…This was proposed by Goto et a1. 2 by analogy with the behavior of 5,6-d2 benzobicyclo (2.2.1) heptane and by Cristol et aL6 by analogy with the behavior of exo-dehydronorbornyl acetate; a direct experimental proof, using 5,6-d2 norbornene, has been provided by D~r s e y .~ The only other fragmentation of norbornene which has aroused interest is the loss of a methyl radical from the molecular ion. Biemann' suggested that this involved breaking the 1 , 7 (or 4, 7) bond followed by migration of a hydrogen atom from the 5 or 6 position to C-7; however, he was of the opinion that his hypothesis would not stand the test of a deuterium labeling experiment because of the possibility of hydrogen scrambling.…”

Section: Introductionmentioning

confidence: 97%

The mass spectra of isomeric hydrocarbons—I: Norbornene and nortricyclene; The mechanisms and energetics of their fragmentations

Holmes

McGillivray

1971

Org. Mass Spectrom.

View full text Add to dashboard Cite

The mass spectra of norbornene, nortricyclene and deuterium labeled derivatives thereof have been studied. The appearance potentials of the ions [G,Hlo]+., [C,H9]+, [C6H7]+ and [C5H,Ii. have been determined for both compounds and heats of formation of the hydrocarbons have been estimated. Detailed fragmentation schemes are proposed for the molecular ions and it is concluded that they dissociate by essentially different mechanisms which do not involve common intermediates. The structures and energy contents of the primary fragment ions are discussed in detail by comparing energetics, labeling experiments and metastable ion abundances.

show abstract

“…The 5-substituted 2-adamantanones are relatively stable under electron impact, except compound 8, and the compounds 1, 5, 6, 9 and 10 show the molecular ion a as a base peak. The fission of the molecular ion a is initiated by the familiar α-cleavage of ketones, which has been shown [18][19][20][21] to produce the most abundant fragments arising from the parent ion. In the present case, α-fission at the C2-C3 bond is attended, possibly in a concerted process, together with simultaneous hydrogen migration to C2, leading to the central intermediate b (Scheme 2).…”

Section: Resultsmentioning

confidence: 99%