18 research outputs found
[RuCl<sub>2</sub>(<i>p-</i>cymene)]<sub>2</sub>‑Catalyzed Conjugate Addition of Arylboronic Acids to α,β-Unsaturated Ketones under Ligand-Free and Neutral Conditions
A simple
and efficient Ru-catalyzed conjugate addition reaction
of arylboronic acids to α,β-unsaturated ketones under
neutral conditions without any additional ligands has been developed.
This RuÂ(II)-catalytic system both fulfilled the inhibition of the
β-hydride elimination in the catalytic cycle and minimized the
protonolysis of arylboronic acids
Enantioselective Synthesis of 1-Aryl-tetrahydroisoquinolines through Iridium Catalyzed Asymmetric Hydrogenation
Asymmetric hydrogenation of 1-aryl-3,4-dihydroisoquinolines using the [IrCODCl]<sub>2</sub>/(<i>R</i>)-3,5-diMe-Synphos catalyst is reported. Under mild reaction conditions, this atom-economical process provides easy access to a variety of enantioenriched 1-aryl-1,2,3,4-tetrahydroisoquinoline derivatives, which are important pharmacophores found in several pharmaceutical drug candidates, in high yields and enantiomeric excesses up to 99% after a single crystallization
Diastereo- and Enantioselective Asymmetric Hydrogenation of α‑Amido-β-keto Phosphonates via Dynamic Kinetic Resolution
Dynamic kinetic resolution of various α-amido-β-keto phosphonates via asymmetric hydrogenation proceeded efficiently to give the corresponding β-hydroxy-α-amido phosphonates in high diastereo- and enantioselectivities (up to 99:1 syn/anti, 99.8% ee). The addition of catalytic amounts of CeCl<sub>3</sub>·7H<sub>2</sub>O is necessary to achieve both good selectivity and catalytic efficiency under mild reaction conditions
Reduction of Benzolactams to Isoindoles via an Alkoxide-Catalyzed Hydrosilylation
An alkoxide-catalyzed
reduction of benzolactams to isoindoles with
silanes was realized. With <i>t</i>-BuOK as the catalyst
and Ph<sub>2</sub>SiH<sub>2</sub> as the reductant, a series of benzolactams
containing different functional groups were reduced to the corresponding
isoindoles, which could be captured by <i>N</i>-phenyl maleimide
to form Diels–Alder products in moderate to good yields. Deuterium
labeling studies and the hydrosilylation of benzolactam in DMF indicated
that the deprotonation of benzolactams took place at C3 potion during
the reduction
Ruthenium-Catalyzed Enantioselective Hydrogenation of Ferrocenyl Ketones: A Synthetic Method for Chiral Ferrocenyl Alcohols
Highly
effective asymmetric hydrogenation of various ferrocenyl
ketones, including aliphatic ferrocenyl ketones as well as the more
challenging aryl ferrocenyl ketones, was realized in the presence
of a Ru/diphosphine/diamine bifunctional catalytic system. Excellent
enantioselectivities (up to 99.8% ee) and activities (S/C = 5000)
could be obtained. These asymmetric hydrogenations provided a convenient
and efficient synthetic method for chiral ferrocenyl alcohols, which
are key intermediates for a variety of chiral ferrocenyl ligands and
resolving reagents
Visible-Light-Induced Photocatalytic Aerobic Oxidation/Povarov Cyclization Reaction: Synthesis of Substituted Quinoline-Fused Lactones
A one-step construction of quinoline-fused
lactones was achieved
by visible-light-induced photocatalytic aerobic oxidation/Povarov
cyclization reaction. This method provides a new access to the synthesis
of important fused heterocycles under mild reaction conditions
Visible Light-Induced Radical Rearrangement to Construct C–C Bonds via an Intramolecular Aryl Migration/Desulfonylation Process
A highly
efficient intramolecular selective aryl migration/desulfonylation
of 2-bromo-<i>N</i>-aryl-<i>N</i>-(arenesulfonyl)Âamide
via visible light-induced photoredox catalysis has been accomplished.
This approach allows for the construction of a variety of multisubstituted <i>N</i>,2-diarylacetamide under mild reaction conditions
Palladium-Catalyzed Amidation of Aryl Halides Using 2‑Dialkylphosphino-2′-alkoxyl-1,1′-binaphthyl as Ligands
Palladium-catalyzed intermolecular C–N bond-forming reactions
between aryl halides and amides are described using 2-dialkylphosphino-2′-alkoxyl-1,1′-binaphthyl,
which is both bulky and electron-rich, as the ligand. A variety of
amides, including aliphatic and aromatic primary amides, lactams,
and carbamates, were viable substrates for the amidation, which exhibited
good functional group compatibility. By tuning the substituents at
the 2,2′-position of 1,1′-binaphthyl of the ligand,
the palladium-catalyzed amidation of bulky aryl halides was realized
and this coupling reaction was used to synthesize 2-amino-2′-methoxy-1,1′-binaphthyl
in high yield
Visible-Light-Induced Radical Cascade Cyclization: Synthesis of the ABCD Ring Cores of Camptothecins
A new strategy for constructing indolizinoÂ[1,2-<i>b</i>]Âquinolin-9Â(11<i>H</i>)-ones (ring cores of camptothecins)
from readily available isocyanoarenes and <i>N</i>-(alkyl-2-yn-1-yl)Âpyridin-2Â(1<i>H</i>)-ones has been developed through a visible-light-induced
radical cascade cyclization process. The reaction proceeds under mild
conditions with fair to excellent yields. The easy introduction of
substituents for both reactants and the broad functional group tolerance
of the reaction make it a straightforward route to the cores of the
marketed camptothecins and their derivatives
Ruthenium-Catalyzed Oxidation of Allyl Alcohols with Intermolecular Hydrogen Transfer: Synthesis of α,β-Unsaturated Carbonyl Compounds
Ruthenium-catalyzed
oxidation of multisubstituted allyl alcohols
in the presence of benzaldehyde gives enals or enones in good yields.
Unlike the commonly reported ruthenium-catalyzed isomerization reaction
of allyl alcohols to give saturated ketones, an intermolecular rather
than intramolecular hydrogen transfer is involved in this transformation.
This reaction offers an efficient, mild, and high-yielding method
for the preparation of substituted α,β-unsaturated compounds