29939-31-9Relevant articles and documents
Structures of Pyridines Obtained in the Aluminum Bromide Mediated Cyclocongregation of Acetylenes with Cyanoformates
Wedinger, R.,Hogeveen, H.,Noble, W. J. le
, p. 1338 - 1341 (1984)
It is shown that the product of the title reaction with tert-butylacetylene and ethyl cyanoformate is not ethyl 3,5-di-tert-butyl-2-picolinate as reported in the recent literature but rather the 4,5-isomer.Varying yields of the 4,6-isomer are also obtained.The NMR spectra described for the 3,5-dimethyl analogue likewise suggest a misassignment of structure in that case.A revised mechanism is tentatively given for these reactions.
Visible Light-Mediated Decarboxylative Alkylation of Pharmaceutically Relevant Heterocycles
Sun, Alexandra C.,McClain, Edward J.,Beatty, Joel W.,Stephenson, Corey R. J.
supporting information, p. 3487 - 3490 (2018/06/26)
A net redox-neutral method for the decarboxylative alkylation of heteroarenes using photoredox catalysis is reported. Additionally, this method features the use of simple, commercially available carboxylic acid derivatives as alkylating agents, enabling the facile alkylation of a variety of biologically relevant heterocyclic scaffolds under mild conditions.
Steric effects on the proton-transfer equilibria of ketones, sulfoxides, and phenols
Bagno, Alessandro,Boso, Renato L.,Ferrari, Nicola,Scorrano, Gianfranco
, p. 1507 - 1515 (2007/10/03)
The proton-transfer equilibrium of several bases and acids, including some sterically hindered ketones, sulfoxides, and phenols, has been investigated by means of the determination of the thermodynamics of the equilibrium, NMR 13C relaxation measurements, and quantum chemical calculations. The analysis of such data yields information about the steric effects on basicity or acidity and about the underlying reasons for the anomalous behavior of species having a sterically hindered basic or acidic site. Thus, it is demonstrated that the anomalously low basicity of two sterically hindered ketones (tBu2CO and PhCOtBu) is enthalpic in origin and stems from steric hindrance to the solvation of their protonated forms. No such effect is found for analogous sulfoxides, whereas phenols display a more complex behavior.
tert-Butylation of Quinolinium Cations and Quinoline N-Oxides by tert-Butylmercury Halides
Russell, Glen A.,Wang, Lijuan,Yao, Ching-Fa
, p. 5390 - 5395 (2007/10/02)
In the presence of t-BuHgCl/KI the radical cations formed by the addition of tert-butyl radicals to C-2 of the quinolinium cation react in Me2SO by proton loss followed by one-electron oxidation (1a, R=H, Me, Cl).For the N-methyl, or N-methoxyquinolinium cations proton loss is not observed and the radical cations react by one-electron reduction (1b, R=Me, Cl; 1c, R=Me).With quinoline N-oxide and its 4-substituted derivatives the C-2 adduct radicals (1d, R=H, Me, Cl) are deprotonated by DABCO to yield after one-electron oxidation the 2-tert-butylquinoline N-oxides.The adduct radical cations formed by t-Bu. addition at the C-4 quinolinium ions 2 seldom lose the C-4 proton but react by reduction, hydration, or in the case of 2-chloroquinoline N-oxide, dimerization.The loss of the proton from the 2-adducts 1 but not from the 4-adducts 2 seems to be stereoelectronic in origin.With N-methylquinolinium cation the addition of t-Bu. occurs selectively (>90percent) at C-4 in contrast to the low selectivity observed in addition to quinolinium ion itself.However, with N-methoxyquinolinium perchlorate the major reaction products (70-90percent) result from the addition of t-Bu. at C-2.
