catalysts based on Al2O3, supercritical carbon dioxide not only acts as a good solvent for the reaction of aromatic and aliphaticaldehydes with 1-nitroalkanes but, most importantly, it also allows the selectivity to be tuned between the competitive formation of beta-nitroalcohols and nitroalkenes (from the Henry reaction and the nitroaldol condensation, respectively). In particular, when the pressure
Organocatalytic Asymmetric Tamura Cycloaddition with α- Branched Nitroolefins: Synthesis of Functionalized 1-Tetralones
作者:Utpal Nath、Subhas Chandra Pan
DOI:10.1021/acs.joc.6b03020
日期:2017.3.17
A new catalyticasymmetricTamuracycloaddition with nitroolefins was developed. This demonstration of the reaction of α-branched nitroolefins with homophthalic anhydrides delivers highly functionalized 1-tetralone compounds. With bifunctional squaramide catalyst, the desired tetralone products are obtained with high enantioselectivity and good diastereoselectivity.
作者:Francesco Manoni、Umar Farid、Cristina Trujillo、Stephen J. Connon
DOI:10.1039/c6ob02637k
日期:——
The first examples of asymmetric Tamura cycloaddition reactions involving singly activated alkenes are reported. Homophthalic anhydride reacts with α-methyl nitrosytrenes in the presence of an alkaloid-based catalyst to generate fused bicyclic aromatic ketone products with three new stereocentres (which are susceptible to subsequent equilibration) in 12–99% ee. An unusual equilibration process which
The reaction of the dianion of β-enaminoketones with electrophiles. Part 6. Synthesis of γ′- and ε-nitro-β-enaminoketones.
作者:Giuseppe Bartoli、Marcella Bosco、Renato Dalpozzo、Antonio De Nino、Gianni Palmieri
DOI:10.1016/s0040-4020(01)85548-4
日期:1994.1
attack the double bond of nitroalkenes affording γ′- and ε-nitro-β-enaminoketones in good to high yields. In contrast to the corresponding 1,3-dicarbonyl dianions, cyclic products from intramolecular Henry reactions are never observed. Quenching the reaction with sulphuric acid ε-nitro-β-enaminoketones are converted in low yields into dihydropyrroles.
作者:Anil K. Saikia、Nabin C. Barua、R. P. Sharma、Anil C. Ghosh
DOI:10.1055/s-1994-25546
日期:——
ß-Nitro alcohols 1 react with triphenylphosphine/carbon tetrachloride/triethylamine under reflux to give the corresponding nitroolefins 2 in good yields (80-95%). Other groups such as tertiary hydroxyl, ether, halide etc. remain unaffected, and the nitroolefins so produced are exclusively the (E)-isomers.