15 research outputs found
Enantioselective Synthesis of Tetrahydroisoquinolines via Iridium-Catalyzed Intramolecular FriedelâCrafts-Type Allylic Alkylation of Phenols
An efficient iridium-catalyzed intramolecular FriedelâCrafts-type allylic alkylation reaction of phenols was developed, affording tetrahydroisoquinolines with moderate to excellent yields, enantioselectivity, and good regioselectivity
Highly Enantioselective Synthesis of Tetrahydrocarbolines <i>via</i> Iridium-Catalyzed Intramolecular FriedelâCrafts Type Allylic Alkylation Reactions
A highly enantioselective synthesis of substituted tetrahydrocarbolines <i>via</i> Ir-catalyzed FriedelâCrafts type intramolecular asymmetric allylic alkylation of 2-indolyl allyl carbonates has been developed. This strategy features excellent chemoselectivity and enantioselectivity, mild reaction conditions, and an easily accessed chiral ligand
Aerobic, Transition-Metal-Free, Direct, and Regiospecific Mono-α-arylation of Ketones: Synthesis and Mechanism by DFT Calculations
We
disclose a facile, aerobic, transition-metal-free, direct, and
regiospecific mono-α-arylation of ketones to yield aryl benzyl
and (cyclo)Âalkyl benzyl ketones with substitution patterns that are
currently inaccessible or challenging to prepare using conventional
methods. The transformation is operationally simple, scalable, and
environmentally friendly. There is no need for pre-functionalization
(i.e., α-halogenation or silyl enol ether formation) or the
use of specialized arylating agents (i.e., diaryliodonium salts).
DFT calculations suggest that the <i>in situ</i>-generated
enolate undergoes direct CâC bond formation with the nitroarene
followed by regioselective O<sub>2</sub>-mediated CâH oxidation
Highly Enantioselective Synthesis of Tetrahydrocarbolines <i>via</i> Iridium-Catalyzed Intramolecular FriedelâCrafts Type Allylic Alkylation Reactions
A highly enantioselective synthesis of substituted tetrahydrocarbolines <i>via</i> Ir-catalyzed FriedelâCrafts type intramolecular asymmetric allylic alkylation of 2-indolyl allyl carbonates has been developed. This strategy features excellent chemoselectivity and enantioselectivity, mild reaction conditions, and an easily accessed chiral ligand
Aerobic, Transition-Metal-Free, Direct, and Regiospecific Mono-α-arylation of Ketones: Synthesis and Mechanism by DFT Calculations
We
disclose a facile, aerobic, transition-metal-free, direct, and
regiospecific mono-α-arylation of ketones to yield aryl benzyl
and (cyclo)Âalkyl benzyl ketones with substitution patterns that are
currently inaccessible or challenging to prepare using conventional
methods. The transformation is operationally simple, scalable, and
environmentally friendly. There is no need for pre-functionalization
(i.e., α-halogenation or silyl enol ether formation) or the
use of specialized arylating agents (i.e., diaryliodonium salts).
DFT calculations suggest that the <i>in situ</i>-generated
enolate undergoes direct CâC bond formation with the nitroarene
followed by regioselective O<sub>2</sub>-mediated CâH oxidation
CâH Bond Functionalization via [1,5]-Hydride Shift/Cyclization Sequence: Approach to Spiroindolenines
A concise synthesis
of spiroindolenines from 2-substituted (Me,
Et) indoles and 2-(pyrrolidin-1-yl)Âbenzaldehydes has been developed
via a [1,5]-hydride shift/cyclization sequence. This method features
a wide substrate scope and an operationally simple procedure, affording
the spiroindolenines in good to excellent yields and moderate diastereoselectivity
(3.5/1 dr). When the inseparable mixture of spiroindolenine isomers
were washed with isopropyl ether after flash chromatography, the major
isomers could be obtained in up to >20/1 dr
Direct Intermolecular CâH Functionalization Triggered by 1,5-Hydride Shift: Access to <i>N</i>âArylprolinamides via Ugi-Type Reaction
A novel
Ugi-type reaction triggered by 1,5-hydride shift has been
established, giving access to <i>N</i>-arylprolinamides
and related compounds in high atom economy and good yields. This is
an example of a two starting materialâthree component reaction.
The benzyl alcohol substrate <b>1</b> acts as a dual synthon,
which upon treatment with a BrĂžnsted acid affords iminium ion
and water. Nucleophilic attack at the iminium ion by the third component
isocyanide, followed by hydrolysis with the endogenic water, gives
the Ugi-type reaction products. The reaction proceeds under mild conditions
and is tolerable to a broad scope of substrates
Stereoselective Synthesis of Arylglycine Derivatives via Palladium-Catalyzed 뱉Arylation of a Chiral Nickel(II) Glycinate
A practical and efficient stereoselective
synthesis of arylglycine
derivatives was realized via palladium-catalyzed α-arylation
of a chiral nickelÂ(II) glycinate complex with aryl bromides. The structurally
diverse arylglycine products were obtained in excellent isolated yields
and with good diastereoselectivity. A simple acidic hydrolysis furnished
optically pure arylglycines in high yield, and the chiral ligand (S)-BPB
could be efficiently recovered and reused
Construction of Oxadiazepines via Lewis Acid-Catalyzed Tandem 1,5-Hydride Shift/Cyclization
Expeditious access to oxadiazepines
via 1,5-hydride shift/cyclization
of pyrrolidine- or tetrahydroisoquinoline-containing nitrones has
been developed. With 1,3-dipole nitrones serving as the hydride acceptors,
this transformation was promoted by a Lewis acid, providing access
to structurally diverse oxadiazepines in good yields. A one-pot process
for in situ nitrone formation, a 1,5-hydride shift, and ring cyclization
was also realized
P<sup>III</sup>/P<sup>V</sup>âCatalyzed Beckmann Reaction and Sequential [2,3]-Sigmatropic Rearrangement to Construct 2âAmidopyridines
An organophosphorus catalytic method for the synthesis
of substituted
2-amidopyridines is reported. The method employs a small-ring organophosphorus-based
catalyst and a hydrosilane reductant to drive the conversion of ketoximes
and pyridine-N-oxides into 2-amidopyridines through
sequential Beckmann rearrangement followed by [2,3]-sigmatropic rearrangement.
The readily available ketoximes could be activated to nitrilium ions
in PIII/PV redox catalysis and could efficiently
participate in the domino reaction of pyridine-N-oxides,
thus providing various substituted 2-amidopyridines in moderate to
excellent yields. This presented strategy features excellent functional
group tolerance and a broad substrate scope