23715-85-7Relevant articles and documents
Reactivity of the 4,5-didehydroisoquinolinium cation
Vinueza, Nelson R.,Archibold, Enada F.,Jankiewicz, Bartlomiej J.,Gallardo, Vanessa A.,Habicht, Steven C.,Aqueel, Mohammad Sabir,Nash, John J.,Kenttaemaa, Hilkka I.
, p. 8692 - 8698 (2012)
The chemical properties of a 1,8-didehydronaphthalene derivative, the 4,5-didehydroisoquinolinium cation, were examined in the gas phase in a dual-cell Fourier-transform ion cyclotron resonance (FT-ICR) mass spectrometer. This is an interesting biradical because it has two radical sites in close proximity, yet their coupling is very weak. In fact, the biradical is calculated to have approximately degenerate singlet and triplet states. This biradical was found to exclusively undergo radical reactions, as opposed to other related biradicals with nearby radical sites. The first bond formation occurs at the radical site in the 4-position, followed by that in the 5-position. The proximity of the radical sites leads to reactions that have not been observed for related mono- or biradicals. Interestingly, some ortho-benzynes have been found to yield similar products. Since ortho-benzynes do not react via radical mechanisms, these products must be especially favorable thermodynamically. Copyright
Photochemical C?H Hydroxyalkylation of Quinolines and Isoquinolines
Bieszczad, Bartosz,Perego, Luca Alessandro,Melchiorre, Paolo
supporting information, p. 16878 - 16883 (2019/11/13)
We report herein a visible light-mediated C?H hydroxyalkylation of quinolines and isoquinolines that proceeds via a radical path. The process exploits the excited-state reactivity of 4-acyl-1,4-dihydropyridines, which can readily generate acyl radicals upon blue light absorption. By avoiding the need for external oxidants, this radical-generating strategy enables a departure from the classical, oxidative Minisci-type pattern and unlocks a unique reactivity, leading to hydroxyalkylated heteroarenes. Mechanistic investigations provide evidence that a radical-mediated spin-center shift is the key step of the process. The method's mild reaction conditions and high functional group tolerance accounted for the late-stage functionalization of active pharmaceutical ingredients and natural products.
Photodissociation Electronic Spectra of Cold Protonated Quinoline and Isoquinoline in the Gas Phase
Féraud, Géraldine,Domenianni, Luis,Marceca, Ernesto,Dedonder-Lardeux, Claude,Jouvet, Christophe
, p. 2580 - 2587 (2017/05/29)
Photofragmentation electronic spectra of isolated single-isomeric N-protonated quinoline (quinolinium) and isoquinoline (isoquinolinium) ions have been measured at a temperature of ～40 K using a mass-selective, 10 cm-1 spectral resolution, photodissociation spectrometer. Additionally, ab initio adiabatic transition energies calculated using the RI-ADC(2) method have been employed to assist in the assignment of the spectra. Three electronic transitions having ππ? character were clearly evidenced for both protonated ions within the UV and deep-UV spectral ranges. The corresponding spectra at room temperature were previously reported by Hansen et al., together with TD-DFT calculations and a careful analysis of the possible fragmentation mechanisms. This information will be complemented in the present study by appending better resolved spectra, characteristic of cold ions, in which well-defined vibrational progressions associated with the S1 ← S0 and S3 ← S0 transitions exhibit clear 0-0 bands at hν0-0 = 27868 and 42230 cm-1, for protonated quinoline, and at hν0-0 = 28043 and 41988 cm-1, for protonated isoquinoline. Active vibrations in the spectra were assigned with the help of calculated normal modes, looking very similar to those of the structurally related protonated naphthalene. Finally, we have observed that the bandwidths associated with the deep-UV S3 ← S0 transition denote a lifetime for the S3 excited state in the subpicosecond time scale, in contrast with that of S1.
