55 research outputs found
Cover Depan Dan Pengantar
A novel strategy for the enantioselective synthesis of 3,3′-disubstituted oxindoles by the organocatalytic Michael addition of indoles to isatylidene-3-acetaldehydes was developed, which can be used for the formal total synthesis of (−)-chimonanthine and the core structure construction of (+)-gliocladin C
Phosphine-Mediated Regio- and Stereoselective Hydrocarboxylation of Enynes
A phosphine-mediated regio- and stereoselective
addition reaction
of diverse nucleophiles to yne-enones leading to polysubstituted 1,3-diene
scaffolds in moderate to good yields has been reported
Lewis Acid-catalyzed [3 + 2]Cyclo-addition of Alkynes with <i>N</i>-Tosyl-aziridines via Carbon–Carbon Bond Cleavage: Synthesis of Highly Substituted 3-Pyrrolines
A novel, efficient, and highly regioselective Lewis acid-catalyzed [3 + 2] cycloaddition of alkynes with azomethine ylides, which are easily obtained from <i>N</i>-tosylaziridines via C–C bond heterolysis at room temperature was developed. Moderate enantioselectivity (70% ee) can be achieved by the application of the commercially available chiral Pybox 7 as the ligand
Phosphine-Catalyzed Asymmetric Synthesis of α‑Quaternary Amine via Umpolung γ‑Addition of Ketimines to Allenoates
A first phosphine-catalyzed
enantioselective umpolung γ-addition
of ketimines to allenoates has been developed that provides efficient
access to optically active γ,δ-unsaturated α-amino
esters and δ-amino esters with a chiral tertiary stereocenter
under mild conditions. The salient features of this reaction include
general substrate scope, mild conditions, good yields, high enantioselectivity,
ease of scale-up to gram scale, and further transformations
Rhodium-Catalyzed Stereoselective Intramolecular Tandem Reaction of Vinyloxiranes with Alkynes: Atom- and Step-Economical Synthesis of Multifunctional Mono‑, Bi‑, and Tricyclic Compounds
Skeletal
diversity in diversity-oriented synthesis has proven to
be especially challenging. A rhodium-catalyzed intramolecular tandem
reaction of vinyloxirane-alkynes leading to four structurally distinct
classes of mono-, bi-, and tricyclic carbocycles and heterocycles
was developed. [RhÂ(NBD)<sub>2</sub>]<sup>+</sup>BF<sub>4</sub><sup>–</sup> is identified to be an efficient catalyst for these
transformations. Using this highly efficient catalyst, hetero-[5 +
2] cycloadditions, tandem hetero-[5 + 2] cycloaddition/Claisen rearrangements,
and subsequent cyclopropane ring-opening reactions of vinyloxiranes
with monoalkynes afford 2,5-dihydrooxepins, tetrasubstituted vinylcyclopropanes,
and multifunctional five-membered rings, respectively, under mild
conditions with high stereoselectivity and yield. Moreover, hetero-[5
+ 2] cycloaddition/Claisen rearrangement/[5 + 2] cycloaddition reactions
of vinyloxiranes with diynes for step-economical construction of linearly
fused 5-7-5 tricyclic skeletons has also been developed. The complete
transfer of chirality from readily available vinyloxiranes to the
corresponding products provides a highly efficient and practical access
to these chiral cyclic compounds
Phosphine-Mediated Regio- and Stereoselective Hydrocarboxylation of Enynes
A phosphine-mediated regio- and stereoselective
addition reaction
of diverse nucleophiles to yne-enones leading to polysubstituted 1,3-diene
scaffolds in moderate to good yields has been reported
Rhodium-Catalyzed Stereoselective Intramolecular Tandem Reaction of Vinyloxiranes with Alkynes: Atom- and Step-Economical Synthesis of Multifunctional Mono‑, Bi‑, and Tricyclic Compounds
Skeletal
diversity in diversity-oriented synthesis has proven to
be especially challenging. A rhodium-catalyzed intramolecular tandem
reaction of vinyloxirane-alkynes leading to four structurally distinct
classes of mono-, bi-, and tricyclic carbocycles and heterocycles
was developed. [RhÂ(NBD)<sub>2</sub>]<sup>+</sup>BF<sub>4</sub><sup>–</sup> is identified to be an efficient catalyst for these
transformations. Using this highly efficient catalyst, hetero-[5 +
2] cycloadditions, tandem hetero-[5 + 2] cycloaddition/Claisen rearrangements,
and subsequent cyclopropane ring-opening reactions of vinyloxiranes
with monoalkynes afford 2,5-dihydrooxepins, tetrasubstituted vinylcyclopropanes,
and multifunctional five-membered rings, respectively, under mild
conditions with high stereoselectivity and yield. Moreover, hetero-[5
+ 2] cycloaddition/Claisen rearrangement/[5 + 2] cycloaddition reactions
of vinyloxiranes with diynes for step-economical construction of linearly
fused 5-7-5 tricyclic skeletons has also been developed. The complete
transfer of chirality from readily available vinyloxiranes to the
corresponding products provides a highly efficient and practical access
to these chiral cyclic compounds
Rhodium-Catalyzed Stereoselective Intramolecular Tandem Reaction of Vinyloxiranes with Alkynes: Atom- and Step-Economical Synthesis of Multifunctional Mono‑, Bi‑, and Tricyclic Compounds
Skeletal
diversity in diversity-oriented synthesis has proven to
be especially challenging. A rhodium-catalyzed intramolecular tandem
reaction of vinyloxirane-alkynes leading to four structurally distinct
classes of mono-, bi-, and tricyclic carbocycles and heterocycles
was developed. [RhÂ(NBD)<sub>2</sub>]<sup>+</sup>BF<sub>4</sub><sup>–</sup> is identified to be an efficient catalyst for these
transformations. Using this highly efficient catalyst, hetero-[5 +
2] cycloadditions, tandem hetero-[5 + 2] cycloaddition/Claisen rearrangements,
and subsequent cyclopropane ring-opening reactions of vinyloxiranes
with monoalkynes afford 2,5-dihydrooxepins, tetrasubstituted vinylcyclopropanes,
and multifunctional five-membered rings, respectively, under mild
conditions with high stereoselectivity and yield. Moreover, hetero-[5
+ 2] cycloaddition/Claisen rearrangement/[5 + 2] cycloaddition reactions
of vinyloxiranes with diynes for step-economical construction of linearly
fused 5-7-5 tricyclic skeletons has also been developed. The complete
transfer of chirality from readily available vinyloxiranes to the
corresponding products provides a highly efficient and practical access
to these chiral cyclic compounds
Enantioselective Phosphine-Catalyzed Allylic Alkylations of <i>mix</i>-Indene with MBH Carbonates
The
first enantioenriched synthesis of 1,1,3-trisubstituted (trifluoromethyl)Âindene
derivatives, bearing a quaternary stereogenic carbon center, is reported
using a simple chiral sulfinamide phosphine-catalyzed asymmetric allylic
alkylation of a mixture of indenes with Morita–Baylis–Hillman
carbonates. The resulting derivatives can serve as a valuable synthetic
building block for some drugs and natural products. Broad substrate
scope and high regio- and enantioselectivity of this reaction were
particularly remarkable
Enantioselective Phosphine-Catalyzed Allylic Alkylations of <i>mix</i>-Indene with MBH Carbonates
The
first enantioenriched synthesis of 1,1,3-trisubstituted (trifluoromethyl)Âindene
derivatives, bearing a quaternary stereogenic carbon center, is reported
using a simple chiral sulfinamide phosphine-catalyzed asymmetric allylic
alkylation of a mixture of indenes with Morita–Baylis–Hillman
carbonates. The resulting derivatives can serve as a valuable synthetic
building block for some drugs and natural products. Broad substrate
scope and high regio- and enantioselectivity of this reaction were
particularly remarkable
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