Proximity effects in the mass spectra of crowded bis(dimethylamino)arenes, I, intramolecular cyclization of ‘proton sponges’ under electron impact

1986 ◽  
Vol 27 (47) ◽  
pp. 5715-5718 ◽  
Author(s):  
Marina Rentzea ◽  
Thomas Saupe ◽  
Heinz A Staab
Keyword(s):  
Electron Impact ◽  
Intramolecular Cyclization ◽  
Mass Spectra ◽  
Proximity Effects ◽  
Proton Sponges

Proximity effects in the electron impact mass spectra of 2-substituted benzazoles

2004 ◽  
Vol 236 (1-3) ◽  
pp. 65-80 ◽  
Author(s):  
Thomas Chantler ◽  
Victoria L. Perrin ◽  
Rachel E. Donkor ◽  
Richard S. Cawthorne ◽  
Richard D. Bowen
Keyword(s):  
Electron Impact ◽  
Mass Spectra ◽  
Proximity Effects ◽  
Electron Impact Mass ◽  
Impact Mass

Mass spectra of 4,4-dimethyl-A-homo-4a,6-cholestadien-3-ols, 4,4-dimethyl-A-homo-5-cholestene-3,4a-diols and their derivatives

1982 ◽  
Vol 47 (10) ◽  
pp. 2768-2778
Author(s):  
Antonín Trka ◽  
Helena Velgová
Keyword(s):  
Carbon Atom ◽  
Electron Impact ◽  
Mass Spectra ◽  
Molecular Ions

Partial electron impact induced mass spectra are given of 3α-hydroxy-, 3β-hydroxy-, 3β-methoxy-, 3α-acetoxy- and 3β-acetoxy-4,4-dimethyl-A-homo-4a,6-cholestadienes, 3α,5α-epoxy-4,4-dimethyl-A-homo-5-cholestane, isomeric 4,4-dimethyl-A-homo-5-cholestene-3α(β),4aα(β)-diols, their 3-acetoxy derivatives and 3-methyl ethers. The fragmentation of the molecular ions of these substances involves the usual elimination of substituents (in the form of H2O, CH3OH, CH3COOH, CH2CO), but the most abundant and characteristic ions are products of the contraction of ring A (to a six- or five-membered one), accompanied by expulsion of a fragment containing the carbon atom C(4) with both methyls.

Cyclopropyl→cyclobutyl rearrangement in intramolecular cyclization of 3,5-bridged B-secoandrostane-6,7(or 5,7)-diols and mass spectra of products

1982 ◽  
Vol 47 (8) ◽  
pp. 2280-2290 ◽  
Author(s):  
Helena Velgová ◽  
Jorga Smolíková ◽  
Antonín Trka ◽  
Antonín Vítek
Keyword(s):  
Intramolecular Cyclization ◽  
Mass Spectra ◽  
Acid Catalyzed

Acid-catalyzed intramolecular cyclization of 6,7-dihydroxy-3α,5-cyclo-6,7-seco-5α-androstan-17-one (VII), 5,7-dihydroxy-3,5-methylene-5,7-secoandrostan-17-one and 5,7-dihydroxy-3β,5-cyclo-5,7-seco-A-homo-5β-androstan-17-one (XIII) in benzene and dioxane was investigated. The main cyclization products were 3,5-methylene-6-oxaandrostan-17-one (I) and/or 3β,5-cyclo-6-oxa-A-homo-5β-androstan-17-one (VIII). In the case of VI and VII the ratio of I and VIII was solvent-dependent: in benzene more VIII was formed than in dioxane. The mass spectra of I and VIII were almost identical and corresponded to the structure VIII.

Sign in / Sign up

Export Citation Format

Share Document