Polarographic reduction of the azines
01 Dec 1970-Journal of the American Chemical Society (American Chemical Society)-Vol. 92, Iss: 24, pp 7154-7160
About: This article is published in Journal of the American Chemical Society.The article was published on 1970-12-01. It has received 124 citations till now.
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TL;DR: The first enantioselective aldehyde α-benzylation using electron-deficient aryl and heteroaryl substrates has been accomplished and the utility of this methodology has been demonstrated via rapid access to an enantioenriched drug target for angiogenesis suppression.
Abstract: The first enantioselective aldehyde α-benzylation using electron-deficient aryl and heteroaryl substrates has been accomplished. The productive merger of a chiral imidazolidinone organocatalyst and a commercially available iridium photoredox catalyst in the presence of household fluorescent light directly affords the desired homobenzylic stereogenicity in good to excellent yield and enantioselectivity. The utility of this methodology has been demonstrated via rapid access to an enantioenriched drug target for angiogenesis suppression.
440 citations
TL;DR: It is shown here how Tetrazines and Supramolecular Applications 3310 have changed over time from simple to complex to supermolecular in simple molecules and how these properties have changed through the ages.
Abstract: 4. Physical Chemistry of Tetrazines 3303 4.1. Electrochemistry of Tetrazines 3303 4.2. Photophysical Properties of Simple Tetrazines 3305 4.3. Computational Chemistry on Tetrazines 3307 5. Applications of Tetrazines 3309 5.1. Energetic Materials from Tetrazines 3309 5.2. NLO-phores with Tetrazine 3309 5.3. Active Polymers Including Tetrazines 3309 5.4. Supermolecular Tetrazines and Supramolecular Applications 3310
318 citations
TL;DR: In this paper, powder X-ray diffraction analysis confirms an alternative structure of a polymer prepared by the method ii. The copolymers have a molecular weight of 5.4 × 103 to 3.3 × 105 and an [η] value of 0.37 to 4.4 dL g-1.
Abstract: Various π-conjugated copolymers constituted of π-excessive thiophene, selenophene, or furan units (Ar) and π-deficient pyridine or quinoxaline (Ar‘) units have been prepared in high yields by the following organometallic polycondensation methods: (i) n X−Ar−Ar‘−X + n Ni(0)Lm → (-Ar−Ar‘)-n (X = halogen, Ni(0)Lm = zerovalent nickel complex), (ii) n X−Ar−X + n Me3Sn−Ar‘−SnMe3 → (-Ar−Ar‘)-n (palladium catalyzed), and (iii) a X−Ar−X + b X−Ar‘−X + (a + b)Ni(0)Lm → (-Ar)x(Ar‘)-y. Powder X-ray diffraction analysis confirms an alternative structure of a polymer prepared by the method ii. The copolymers have a molecular weight of 5.4 × 103 to 3.3 × 105 and an [η] value of 0.37 to 4.4 dL g-1. π−π* absorption bands of the copolymers generally show red shifts from those of the corresponding homopolymers, (-Ar)-n and (-Ar‘)-n, and the red shifts are accounted for by charge-transferred CT structures of the copolymers. For example, an alternative copolymer of thiophene and 2,3-diphenylquinoxaline gives rise to an absorp...
304 citations
TL;DR: In this paper, the electron affinities for benzene, pyridine, diazines, pyrazine, and s−triazine were determined from the present experiment (−1.15 eV and −0.62 eV for C5H5N).
Abstract: Electron transmission spectroscopy is used to study shape resonances (temporary negative ions) in benzene and some isolectronic N−heterocyclic molecules (pyridine, diazines, and s−triazine), in the energy range 0−6 eV. The lowest shape resonance in each of these molecules exhibits vibrational structure which is interpreted in all cases as the totally symmetric C−C stretch mode. The ground vibrational level of this lowest shape resonance is accessible by electron impact only in benzene and pyridine. Thus, their electron affinities can be determined from the present experiment (−1.15 eV for C6D6 and −0.62 eV for C5H5N). Only excited vibrational levels are accessible in the diazines and s−triazine, indicating that the electron affinities for these molecules have positive values. For benzene, pyridine, and some other aromatic hydrocarbons, we compare the electron affinities established in the gas phase with the polarographic potentials established in the liquid phase and we find a linear relationship. Using this correlation in conjunction with the measured values of the polarographic potentials, we estimate the electron affinities for pyridazine (0.25 eV), pyrimidine (0 eV), pyrazine (0.40 eV) and s−triazine (0.45 eV).
290 citations