27 research outputs found
Asymmetric Michael Addition of Ketones to Alkylidene Malonates and Allylidene Malonates via EnamineāMetal Lewis Acid Bifunctional Catalysis
Novel enamineāmetal Lewis acid bifunctional catalysts
were
successfully applied to the asymmetric Michael addition of ketones
to alkylidene malonates, offering excellent stereoselectivity (up
to >99% <i>ee</i> and >99:1 <i>dr</i>).
The asymmetric
Michael addition of ketones to allylidene malonates was also achieved
Asymmetric Michael Addition of Ketones to Alkylidene Malonates and Allylidene Malonates via EnamineāMetal Lewis Acid Bifunctional Catalysis
Novel enamineāmetal Lewis acid bifunctional catalysts
were
successfully applied to the asymmetric Michael addition of ketones
to alkylidene malonates, offering excellent stereoselectivity (up
to >99% <i>ee</i> and >99:1 <i>dr</i>).
The asymmetric
Michael addition of ketones to allylidene malonates was also achieved
Cu-Catalyzed Three-Component Coupling of Aryne, Alkyne, and Benzenesulfonothioate: Modular Synthesis of <i>o</i>āAlkynyl Arylsulfides
A copper-catalyzed
three-component coupling reaction of in situ formed arynes, terminal
alkynes, and benzenesulfonothioates is described. This reaction provides
an efficient modular synthesis of <i>o</i>-alkynyl arylsulfides
from easily available starting materials. This process involves one
CāS bond and one CāC bond formation in one pot
Atom Transfer Radical Addition to Alkynes and Enynes: A Versatile Gold/Photoredox Approach to Thio-Functionalized Vinylsulfones
An
efficient intermolecular atom-transfer addition reaction of
alkynes via the combination of visible-light photoredox catalysis
and gold catalysis has been developed, affording diverse trifluoromethylthio-
and difluoromethylthio-functionalized vinylsulfones with high stereoselectivity
in good yields. Thiosulfonylation reaction of enyne can also be realized
for constructing functionalized carbo- and heterocycles through a
radical cascade cyclization process. These reactions proceed through
a gold-assisted sulfonyl radical addition pathway
Copper-Catalyzed Oxidative Trifunctionalization of Olefins: An Access to Functionalized Ī²āKeto Thiosulfones
Aerobic
oxidative trifunctionalization of olefins for the synthesis
of functionalized Ī²-keto thiosulfones has been described. The
transformation proceeds through molecular oxygen activation under
copper catalysis and forms the two new CāS bonds in a single
operation using mild conditions. A novel Cu-catalyzed sulfonyl radical
addition/oxidation/funtionalization relay mechanism was proposed for
the discovered reaction
Atom Transfer Radical Addition to Alkynes and Enynes: A Versatile Gold/Photoredox Approach to Thio-Functionalized Vinylsulfones
An
efficient intermolecular atom-transfer addition reaction of
alkynes via the combination of visible-light photoredox catalysis
and gold catalysis has been developed, affording diverse trifluoromethylthio-
and difluoromethylthio-functionalized vinylsulfones with high stereoselectivity
in good yields. Thiosulfonylation reaction of enyne can also be realized
for constructing functionalized carbo- and heterocycles through a
radical cascade cyclization process. These reactions proceed through
a gold-assisted sulfonyl radical addition pathway
In Situ Construction of Three Anion-Dependent Cu(I) Coordination Networks as Promising Heterogeneous Catalysts for AzideāAlkyne āClickā Reactions
Three CuĀ(I) coordination networks,
namely, {[Cu<sub>2</sub>(bpz)<sub>2</sub>Ā(CN)ĀX]Ā·CH<sub>3</sub>CN}<sub><i>n</i></sub>, (X = Cl, <b>1</b>;
I, <b>3</b>), {[Cu<sub>6</sub>(bpz)<sub>6</sub>Ā(CH<sub>3</sub>CN)<sub>3</sub>Ā(CN)<sub>3</sub>Br]Ā·2OHĀ·14CH<sub>3</sub>CN}<sub><i>n</i></sub>, (<b>2</b>, bpz = 3,3ā²,5,5ā²-tetramethyl-4,4ā²-bipyrazole),
were prepared by using solvothermal method. The cyanide ligands in
these networks were generated in situ by cleavage of CāC bond
of MeCN under solvothermal condition. The structures of these networks
are dependent on halogen anions. Complex <b>1</b> is a ladderlike
structure with Ī¼<sub>2</sub>-CN<sup>ā</sup> as rung and
Ī¼<sub>2</sub>-bpz as armrest. The Cl<sup>ā</sup> in <b>1</b> is at terminal position but does not extend the one-dimensional
(1D) ladder to higher dimensionalities. Complex <b>2</b> is
a three-dimensional (3D) framework comprised of novel planar [Cu<sub>3</sub>Br] triangle and single Cu nodes, which are extended by Ī¼<sub>2</sub>-bpz and Ī¼<sub>2</sub>-CN<sup>ā</sup> to form
a novel (3,9)-connected <b>gfy</b> network. Density functional
theory calculations showed that single-electron delocalization of
Br atom induces the plane structure of [Cu<sub>3</sub>Br]. Complex <b>3</b> also possesses a similar ladderlike subunit as in <b>1</b>, but the I<sup>ā</sup> acts as bidentate bridge to
extend the ladder to 3D framework with a four-connected <b>sra</b> topology. The three networks show notable catalytic activity on
the click reaction. The compared catalytic results demonstrate that
complex <b>2</b> possesses the best catalysis performance among
three complexes, which is ascribed to the largest solvent-accessible
void (porosity: <b>2</b> (29.4%) > <b>1</b> (25.7%)
> <b>3</b> (17.6%)) and the more CuĀ(I) active sites in <b>2</b>. The present combined structureāproperty studies
provide not only a new synthetic route to obtain a new kind of catalyst
for click reaction but also the new insights on catalyst structureāfunction
relationships
Copper(I)-Catalyzed Three-Component Click/Persulfuration Cascade: Regioselective Synthesis of Triazole Disulfides
A copperĀ(I)-catalyzed
three-component CuAAC/persulfuration reaction
providing rapid access to asymmetric triazole disulfides has been
developed. The interrupted click reaction shows broad substrate scope,
complete regioselectivity, and excellent functional group tolerability
Copper(I)-Catalyzed Three-Component Click/Alkynylation: One-Pot Synthesis of 5āAlkynyl-1,2,3-triazoles
A copperĀ(I)-catalyzed
tandem CuAAC/alkynylation reaction of various
alkynes, organic azides, and bromoalkynes to provide rapid access
to 5-alkynyl-1,2,3-triazoles has been developed. The reaction proceeded
via a copper-catalyzed alkyne azide cycloaddition followed by interception
of the in situ formed cuprateātriazole intermediate with bromoalkyne.
This reaction offers a new method to afford fully substituted triazoles
in high yields with complete regioselectivity under mild reaction
conditions