A metal-free, photocatalyst-free, photochemical system was developed for the direct alkylation of thiophenols via electron donor− acceptor (EDA) complexes (K EDA = 145 M −1 ) between two reactants, Nhydroxyphthalimide esters as acceptors and thiophenol anions as donors, in the presence of a tertiary amine. The EDA complexes in the reaction system have a broad range of visible-light absorption (400−650 nm) and can trigger the reaction effectively under sunlight.
There
are some synthesis methods from widely available aldehydes
to the corresponding ketones, however, they involved in multistep
reactions with Grignard’s reagents or transition metal catalysts.
In this paper, we have developed photocatalyst-free and visible light-driven
decarboxylative alkylation of pyridinaldehydes. The photochemical
reactions are initiated via photoinduced single electron transfer
from triethylamine to N-hydroxyphthalimide esters
in electron donor–acceptor complexes. This photochemical method
can achieve to translate 15 pyridinaldehydes and 11 2-quinolinaldehydes
to the corresponding ketones. Furthermore, this strategy can also
achieve two other transformations, disulfanes to aryl sulfides and
a styrene sulfone to the alkyl-substituted alkene.
Abstract:The solute-solvent interactions of 4-nitro-1,8-naphthalimide (4NNI) as a hydrogen bond acceptor in hydrogen donating methanol (MeOH) solvent in electronic excited states were investigated by means of the timedependent density functional theory(TDDFT). We calculated the S 0 state geometry optimizations, electronic transition energies and corresponding oscillation strengths of the low-lying electronically excited states for the isolated 4NNi and hydrogen-bonded 4NNi-(MeOH) 1,4 complexes using the density functional theory (DFT) and TDDFT methods. The electronic excitation energies of the hydrogen-bonded complexes are correspondingly decreased compared to that of the isolated 4NNi, which revealed that the intermolecular hydrogen bond C=O· · · H-O and N=O· · · H-O in the hydrogen-bonded 4NNi-(MeOH) 1,4 are strengthened in the electronically excited state. The calculated results are consistent with the mechanism that hydrogen bond strengthening will induce a redshift of the corresponding electronic spectra, while hydrogen bond weakening will cause a blueshift. Furthermore, we believe that the deduction we used to depict the trend of the hydrogen bond changes in excited states exists in many other fluorescent dyes in solution.
A facile
and effective synthesis of 2-chloromethylpyridines was
developed by a one-pot reaction of 2-alkylpyridin-N-oxides and triphosgene at room temperature. As starting materials, N-oxides of 2-alkylpyridine derivatives, including 2-alkylpyridines,
2-methyl quinolines, and phenanthroline, can react rapidly with triphosgene
in the presence of triethylamine, affording 2-chloromethylpyridines
in good to excellent yields (52–95%). Using the 2-methylquinoline
substrate for the mechanistic study, it has been well demonstrated
that the chlorination reaction undergoes a [3,3]-sigmatropic rearrangement,
which can be observed as a reversible process by monitoring the intermediates.
Moreover, the chlorination reaction can be used to construct a rapid
and sensitive fluorescent probe for the detection of phosgene.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.