We herein disclose the use of tetramethylammonium fluoride (TMAF) as a direct and selective methylating agent of a variety of amides, indoles, pyrroles, imidazoles, alcohols, and thiols. The method ...is characterized by operational simplicity, wide scope, and ease of purification. Our computational studies suggest a concerted methylation–deprotonation as the preferred reaction pathway.
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IJS, KILJ, NUK, PNG, UL, UM
An efficient protocol for the asymmetric synthesis of fluorenols has been developed through an enantioconvergent process enabled by Pd(ii)/chiral norbornene cooperative catalysis. This approach ...allows facile access to diverse functionalized chiral fluorenols with constantly excellent enantioselectivities, applying readily available racemic secondary
-bromobenzyl alcohols and aryl iodides as the starting materials.
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IJS, KILJ, NUK, UL, UM, UPUK
A palladium-catalyzed 4 + 3 annulation of 2-bromobiphenyls and epoxides for the construction of dihydrodibenzo
b
,
d
oxepines is reported. This approach involves direct CH and C-O bond activation ...followed by a ring annulation and features readily available starting materials, a broad substrate scope, good step economy and good scalability.
A palladium-catalyzed 4 + 3 annulation of 2-bromobiphenyls and epoxides for the construction of dihydrodibenzo
b
,
d
oxepines is reported.
Reported is a modular strategy for the preparation of the unique benzofused dioxabicycle scaffolds involving a Catellani reaction of aryl iodides, epoxides, and terminal alkynes and an ...oxa-cyclization. This is a mild, scalable, chemoselective, and atom-economical protocol, compatible with various functionalized aryl iodides, epoxides, and terminal alkynes. With the ability to build up the molecular complexity rapidly and efficiently from feedstock chemicals, this method will have wide applications in organic synthesis.
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C–N axially chiral skeletons are ubiquitous in bioactive natural products, pharmaceuticals, and chiral ligands. However, their atroposelective synthesis remains a formidable challenge because of ...their innate low configurational stability compared with that of well-developed C–C atropisomers. Herein, we report a general and efficient method for accessing C–N atropisomers through an axial-to-axial chirality transfer strategy based on palladium/chiral norbornene cooperative catalysis. The obtained C–N axial chirality originates from the preformed transient C–C axial chirality with high fidelity. A variety of C–N axially chiral phenanthridinones are obtained in excellent enantioselectivities (44 examples, up to >99% ee). This method can be applied for the construction of two stereogenic axes via double atroposelective C–H arylation or further transformation of the products via axial-to-axial diastereoinduction. Additionally, the reaction mechanism and the chirality transfer process are elucidated by density functional theory calculations.
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•Unique axial-to-axial chirality transfer for C–N axial chirality construction•Ability to assemble two vicinal and remote stereogenic axes•Step-economic and scalable synthesis of enantioenriched phenanthridinones•Broad scope, good yields, and excellent enantioselectivities
Axial chirality widely exists in bioactive natural products, pharmaceuticals, chiral materials, and chiral ligands and catalysts in asymmetric catalysis. As such, the efficient, modular, and enantioselective assembly of these scaffolds from readily available starting materials represents one of the most challenging yet fascinating directions in synthetic organic chemistry. In sharp contrast to the well-developed C–C axial chirality, atroposelective construction of C–N axial chirality has been less investigated because of the innate higher degree of rotational freedom of the latter. Herein, we report an efficient atroposelective construction of C–N atropisomers via palladium/chiral norbornene cooperative catalysis. The key to success is the unique axial-to-axial chirality transfer process, which has been scarcely reported. This strategy is expected to inspire future studies in asymmetric synthesis and find applications in broad research fields.
C–N axially chiral skeletons are prevalent in bioactive natural products and pharmaceuticals. However, their atroposelective synthesis remains a formidable challenge. Herein, an efficient method for the synthesis of C–N axially chiral phenanthridinones through palladium/chiral norbornene cooperative catalysis is reported. The strategy involves a unique axial-to-axial chirality transfer process, which has been scarcely reported. DFT calculations are performed to elucidate the reaction mechanism and the chirality transfer process, providing broader implications for future studies in asymmetric synthesis.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Comprehensive Summary
Flavones and isoflavones are recognized as privileged heterocyclic scaffolds for the preparation of bioactive compounds. Efficient methods to access these heterocycles are in ...urgent need. Herein, we report diversity‐oriented synthesis of flavones and isoflavones from 3‐iodochromones via palladium/norbornene cooperative catalysis. The success of this research relies on the use of a unique bridge‐head ester modified norbornene derivative as the mediator. Salient features of this include readily available starting materials regarding 3‐iodochromones, ortho‐C—H arylating and alkylating reagents and ipso‐terminating reagents, broad substrate scope, good chemoselectivity, good step‐economy and scalability. A large number of structurally diversified flavones, isoflavones and 2,3‐diarylated chromones can be quickly prepared in a predictable manner. As showcased by the efficient formal synthesis of umbralisib, this chemistry can be treated as another valuable addition to the toolbox of medicinal chemists.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Autophagy is an evolutionarily conserved 'self-eating' process. Although the genes essential for autophagy (named Atg) have been identified in yeast, the molecular mechanism of how Atg proteins ...control autophagosome formation in mammalian cells remains to be elucidated. Here, we demonstrate that Bif-1 (also known as Endophilin B1) interacts with Beclin 1 through ultraviolet irradiation resistance-associated gene (UVRAG) and functions as a positive mediator of the class III PI(3) kinase (PI(3)KC3). In response to nutrient deprivation, Bif-1 localizes to autophagosomes where it colocalizes with Atg5, as well as microtubule-associated protein light chain 3 (LC3). Furthermore, loss of Bif-1 suppresses autophagosome formation. Although the SH3 domain of Bif-1 is sufficient for binding to UVRAG, both the BAR and SH3 domains are required for Bif-1 to activate PI(3)KC3 and induce autophagosome formation. We also observed that Bif-1 ablation prolongs cell survival under starvation conditions. Moreover, knockout of Bif-1 significantly enhances the development of spontaneous tumours in mice. These findings suggest that Bif-1 joins the UVRAG-Beclin 1 complex as a potential activator of autophagy and tumour suppressor.
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DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Herein, we report a modular and convergent strategy for the assembly of atropisomeric o-terphenyls with 1,2-diaxes via palladium/chiral norbornene cooperative catalysis and axial-to-axial ...diastereoinduction. Readily available aryl iodides, 2,6-substituted aryl bromides, and potassium aryl trifluoroborates are used as the building blocks, laying the foundation for diversity-oriented synthesis of these scaffolds (46 examples). Other features include the unique axial-to-axial diastereoinduction mode, construction of two axes in a single operation, and step economy. DFT calculations are performed to rationalize the axial-to-axial diastereoinduction process. Synthetic utilities of this method in preparation of atropisomeric oligophenyls, chiral catalysts, and ligands are demonstrated.
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IJS, KILJ, NUK, PNG, UL, UM
Reported is the borono-Catellani arylation process for unsymmetrical biaryls synthesis, utilizing the readily available pinacol ester of arylboronic acids, aryl bromides, and olefins as the ...reactants. The distinct reactivity of arylboronic ester and aryl bromides secures the excellent chemoselectivity in the pivotal arylation step. The reaction is enabled by the cooperative catalysis of Pd(OAc)2 and the NBE derivative N 7 , with molecular oxygen as the terminal oxidant.
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•A novel strategy to prepare Fe, N and S tri-doped graphene (Fe-N-S-GR) is reported.•The codoping of Fe, N and S is essential for the formation of Pt nanodendrites (NDs).•The Pt ...NDs/Fe-N-S-GR catalyst exhibits much higher MOR electrocatalytic properties.•DFT studies reveal the mechanism of Pt NDs/Fe-N-S-GR for enhanced MOR properties.
Multiatom-doped carbon nanomaterials have emerged as very promising electrocatalysts for fuel cell applications because of the synergistic electron effect that occurs between the hetero-dopants. However, their electrochemical properties strongly depend on the structural design of the doped heteroatoms, and a fundamental understanding of their electrocatalytic mechanism is still a challenge. Herein, a novel and effective sulfonated iron phthalocyanine pyrolysis strategy to synthesize Fe, N, and S tri-doped graphene nanohybrids is reported, and this hybrid is utilized as the catalyst support for highly efficient Pt nanodendrites. In this strategy, the incorporation of S atoms is rationally engineered by the sulfonate groups in the phthalocyanine molecules, and it leads to the uniform distribution of an active FeNx-S2 configuration in the graphene structure, along with the Fe and N atoms. The Pt nanodendrites assembled on Fe, N, and S tri-doped graphene exhibit a much higher electrocatalytic activity and long-term electrochemical durability for methanol oxidation. Both controlled experiments and density functional theory calculations reveal that the co-doping of Fe, N, and S atoms is beneficial for the formation of dendritic Pt nanoparticles and the electrochemical performance enhancement of Pt nanodendrites. The density functional theory calculations indicate that the co-doping of Fe, N, and S atoms not only increases the ability to adsorb Pt and the catalyst durability, but also enhances the CO tolerance ability and prevents the poisoning effect during methanol oxidation. This study demonstrates a new method for the controllable synthesis of multi-doped graphene-based electrocatalysts with optimized surface structures and electrochemical performances.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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