The activation energy of the skeletal isomerization in the radical cations of toluene and cycloheptatriene by mass spectrometry of their 2-phenylethyl derivatives

Kuck D, Grützmacher H-F. The activation energy of the skeletal isomerization in the radical cations of toluene and cycloheptatriene by mass spectrometry of their 2-phenylethyl derivatives. Organic Mass Spectrometry. 1979;14(2):86-97

Interannular proton exchange in protonated long-chain 1, [omega]-diphenylalkanes

Kuck D, Bäther W, Grützmacher H-F. Interannular proton exchange in protonated long-chain 1, [omega]-diphenylalkanes. International Journal of Mass Spectrometry and Ion Processes. 1985;67(1):75-91

Gaseous [CnH2n+1+ ... 1,3-Diphenylpropane] Ion/Neutral Complexes Containing Alkyl Cations of Different Acidities and Hydride Ion Affinities

Gaseous ion/neutral (I/N) complexes [R+ ... C6H5CH2CH2CH2C6H5] with R = t-C4H9+, s-C4H9+ and s-C3H7+ have been generated by protonation of the corresponding precursor compounds, R-C6H4CH2CH2CH2C6H5, in the chemical ionisation (CI) source of a sector-field mass spectrometer. The fragmentation of these I/N complexes and several deuterium-labelled isotopologues on the metastable ions’ timescale (20−30 μs), as studied by MIKE spectrometry, revealed that (i) the initial ring position (meta- or para-) of R = t-C4H9+ does not affect their intra-complex reactivity, (ii) the fragmentation of the s-C3H7+ and s-C4H9+ ions is dominated by proton transfer to the 1,3-diphenylpropane neutral but hydride ion abstraction in the reverse direction competes to a minor extent, (iii) the secondary alkyl cations exhibit the same regioselectivity (kα-H/kω-H = 1.0) and kinetic isotope effect (kH/kD = 1.6) in the hydride transfer channel as do tertiary alkyl cations, (iv) the s-C4H9+ ions do not undergo skeletal isomerisation to t-C4H9+ ions within the I/N complex. Attempts to characterise the trimethylsilyl complex, [Si(CH3)3 + ∙∙∙ C6H5CH2CH2CH2C6H5], by CI/MIKE spectrometry under analogous conditions failed

Oxidations of alkylbenzenes with dimethyldioxirane

Kuck D, Schuster A. Oxidations of alkylbenzenes with dimethyldioxirane. Zeitschrift für Naturforschung B, Journal of Chemical Sciences. 1991;46(9):1223-1226.The oxidation of various alkylbenzenes (1-17) with excess dimethyldioxirane (DMDO) in homogeneous acetone solutions has been studied. In general, the benzylic methylene and methine C-H bonds were oxidized to give the corresponding phenones and tertiary benzylic alcohols, respectively, in relatively low yields. Whereas a tert-butyl substituent at the reaction centre leads to very low conversion due to steric hindrance, the presence of additional phenyl groups appears to favour the oxidation in most, but not all cases. Di- and triphenylmethane (4 and 14) were found to be considerably less reactive than cis-decalin. By contrast, the intramolecular competitive oxidation of isobutylbenzene (19) and 1-methyl-4-phenylcyclohexanes (20) reveals that the benzylic C-H bonds are slightly more reactive than the tertiary ones at remote positions

INFLUENCE OF THE CHAIN-LENGTH ON THE MASS-SPECTROMETRIC FRAGMENTATION OF HIGHER 1, OMEGA-DIPHENYLALKANES

Kuck D, Grützmacher H-F. Der Einfluß der Kettenlänge auf die massenspektrometrische Fragmentierung höherer 1.[Omega]-Diphenylalkane. Zeitschrift für Naturforschung B, Journal of Chemical Sciences. 1979;34(12):1750-1764

BENZOANNELATED CENTROPOLYQUINANES .3. SYNTHESIS OF MULTIPLY SUBSTITUTED TRIPTINDANS (9H,10H-4B,9A-([1,2]BENZENOMETHANO)INDENO[1,2-ALPHA]INDENES) WITH SUBSTITUENTS IN THEIR MOLECULAR CAVITY

Kuck D, Paisdor B, Grützmacher H-F. Benzoanellierte Centropolyquinane, 3 Synthese mehrfach substituierter Triptindane (9H, 10H-4b, 9a-([1,2]Benzenomethano)indeno[1,2-a]indene) mit drei Substituenten in ihrer Molekülhöhlung. Chemische Berichte. 1987;120(4):589-595.The synthesis of triptindans 13a - e substituted by methoxy and/or methyl groups in positions 2,4,5,7,13, and 15 has been achieved by acid-catalysed cyclodehydration of the corresponding 2,2-dibenzyl-1-indanones 12a - e using Amberlyst 15 and polyphosphoric acid, respectively. Total demethylation of 13a followed by selective deoxygenation of the resulting hexahydroxy compound 14 affords the 4,5,15-trihydroxytriptindan (17) (4, R=OH) bearing the three substituents in its molecular cavity.Die Synthese der Triptindane 13a - e mit Methoxy- und/oder Methylsubstituenten in den Positionen 2,4,5,7,13 und 15 gelingt durch sauer katalysierte Cyclodehydratisierung entsprechend substituierter 2,2-Dibenzyl-1-indanone 12a - e mit Amberlyst 15 beziehungsweise Polyphosphorsäure. Die vollständige Demethylierung von 13a führt zur Hexahydroxyverbindung 14, die durch selektive Desoxygenierung in das 4,5,15-Trihydroxytriptindan (17), (4, R=OH) umgewandelt werden kann. 17 besitzt drei Hydroxysubstituenten, die in die Molekülhöhlung gerichtet sind

BENZOANNELATED CENTROPOLYQUINANES .4. STERIC EFFECTS IN MULTIPLY SUBSTITUTED TRIPTINDANS (9H,10H-4B,9A-([1,2]BENZENOMETHANO)INDENO[1,2-A]INDENES)

Paisdor B, Grützmacher H-F, Kuck D. Benzoanellierte Centropolyquinane, 4. Sterische Effekte in mehrfach substituierten Triptindanen (9H, 10H-4b, 9a-([1,2]Benzenomethano)indeno[1,2-a]indenen). Chemische Berichte. 1988;121(7):1307-1313.Die sterischen Wechselwirkungen von drei Substituenten in den endo-Positionen 4, 5 und 15 von Triptindan (6) gestatten bei der Cyclodehydratisierung der 1-Indanone 11, 12 und 14 nur den Einbau jeweils einer Methylgruppe in die Molekülhöhlung. Diese Regioselektivität wird durch DNMR-Messungen und Kraftfeld-Rechnungen an den Triptindanen 1-5 auf die erhebliche Kompression in den Rotameren A und A der Triptindane mit bereits zwei endo-Methylgruppen zurückgeführt

Gaseous [M - H]+ ions of alpha,omega-diphenylalkanes: cyclization to [M + H]+ type ions of benzocycloalkanes as recognized by chain-length dependent proton exchange

Kuck D. Gaseous [M - H]+ ions of alpha,omega-diphenylalkanes: cyclization to [M + H]+ type ions of benzocycloalkanes as recognized by chain-length dependent proton exchange. International Journal of Mass Spectrometry and Ion Processes. 1992;117(1-3):441-455.Metastable [M - H]+ ions of alpha,omega-diphenylalkanes C6H5(CH2)xC6H5 where x = 3-6 (structures 3-6 respectively), generated by hydride abstraction in the chemical ionization (i-butane) source, eliminate benzene after proton exchange between the aromatic rings. The proton exchange is slow for ions [3 - H]+ and [4 - H]+, but fast and apparently complete for ions [5 - H]+ and [6 - H]+. These observations, combined with collision activation experiments, suggest the cyclization of the [M - H]+ ions to isomeric protonated 1-phenylbenzocycloalkane and 1-benzylbenzocycloalkane derivatives, i.e. to [M1 + H]+ type ions, with a preference for protonated tetralin structures. Hydrogen exchange between the aliphatic chain and the rings is absent or negligible for [M - H]+ ions of 3-5 but is significant for ions [6 - H]+

Benzoannelated centropolyquinanes. 2. (all-cis)-Tetrabenzotetracyclo[5.5.1.0(4,13).0(10,13)]tridecane, "Fenestrindan"

Kuck D, Bögge H. Benzoannelated centropolyquinanes. 2. (all-cis)-Tetrabenzotetracyclo[5.5.1.0(4,13).0(10,13)]tridecane, "Fenestrindan". Journal of the American Chemical Society. 1986;108(25):8107-8109