Skeletal reorganization reactions have emerged as an intriguing tool for converting readily available compounds into complicated molecules inaccessible by traditional methods. Herein, we report a ...unique skeleton‐reorganizing coupling reaction of cycloheptatriene and cycloalkenones with amines. In the presence of Rh/acid catalysis, cycloheptatriene can selectively couple with anilines to deliver fused 1,2‐dihydroquinoline products. Mechanistic studies indicate that the retro‐Mannich type ring‐opening and subsequent intramolecular Povarov reaction account for the ring reorganization. Our mechanistic studies also revealed that skeleton‐reorganizing amination between anilines and cycloalkenones can be achieved with acid. The synthetic utilization of this skeleton‐reorganizing coupling reaction was showcased with a gram‐scale reaction, synthetic derivatizations, and the late‐stage modification of commercial drugs.
An unusual catalytic coupling reaction of cycloheptatriene and cycloalkenones with amines proceeds through a skeleton‐reorganization process for the selective synthesis of fused 1,2‐dihydroquinolines. Mechanistic studies indicate that the reactions proceed through a retro‐Mannich‐type ring‐opening and a subsequent intramolecular Povarov process.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Depending on the reactant property and reaction mechanism, one major regioisomer can be favored in a reaction that involves multiple active sites. Herein, an orthogonal regulation of nucleophilic and ...electrophilic sites in the regiodivergent hydroamination of isoprene with indazoles is demonstrated. Under Pd‐hydride catalysis, the 1,2‐ or 4,3‐insertion pathway with respect to the electrophilic sites on isoprene could be controlled by the choice of ligands. In terms of the nucleophilic sites on indazoles, the reaction occurs at either the N1‐ or N2‐position of indazoles is governed by the acid co‐catalysts. Preliminary experimental studies have been performed to rationalize the mechanism and regioselectivity. This study not only contributes a practical tool for selective functionalization of isoprene, but also provides a guide to manipulate the regioselectivity for the N‐functionalization of indazoles.
The Pd‐catalyzed regiodivergent coupling reactions between indazoles and isoprene have been developed through the orthogonal regulation of nucleophilic and electrophilic sites.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Transition metal catalyzed decarbonylation offers a distinct synthetic strategy for new chemical bond formation. However, the π‐backbonding between CO π* orbitals and metal center d‐orbitals impedes ...ligand dissociation to regenerate the catalyst under mild reaction conditions. Developed here is visible light induced rhodium catalysis for decarbonylative coupling of imides with alkynes under ambient conditions. Initial mechanistic studies suggest that the rhodium complex simultaneously serves as the catalytic center and photosensitizer for decarbonylation. This visible light promoted catalytic decarbonylation strategy offers new opportunities for reviewing old transformations with ligand dissociation as a rate‐determining step.
Visible light induced rhodium catalysis has been developed for decarbonylative coupling of imides with alkynes under ambient conditions. Initial mechanistic studies suggest that the rhodium complex simultaneously serves as the catalytic center and photosensitizer for decarbonylation.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Terpenes, consisting of isoprene monomer units, represent a family of naturally abundant compounds. The difunctionalization of terpenes is highly appealing yet remains challenging, since the multiple ...unbiased C&z.dbd;C bonds of terpenes lead to difficulty in controlling the regioselectivity. Herein, a cobalt(
iii
)-catalyzed C-H activation strategy has been developed to facilitate hydroxymethylarylation of terpenes with formaldehyde and arenes with high chemo- and regio-selectivities. These (chemo- and regio-) selectivities are governed by the coordination abilities of isoprene, directing groups and the steric effect. This terpene difunctionalization also features high atom and step economy through a C-H addition pathway.
A cobalt(
iii
)-catalyzed C-H activation strategy has been developed to facilitate hydroxymethylarylation of terpenes with formaldehyde and arenes with high chemo- and regio-selectivities.
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IJS, KILJ, NUK, UL, UM, UPUK
The Mizoroki-Heck reaction and its reductive analogue are staples of organic synthesis, but the ensuing products often lack a chemical handle for further transformation. Here we report an ...atom-economical cross-coupling of halopyridines and unactivated alkenes under photoredox catalysis to afford a series of alkene halopyridylation products. This protocol with mild and redox neutral conditions contributes broad substrate scope. As a complement to conventional Heck-type reaction, this radical process avoids the involvement of β-H elimination and thus useful pyridyl and halide groups could be simultaneously and regioselectively incorporated onto alkenes. The success depends on TFA-promoted domino photocatalytic oxidative quenching activation and radical-polar crossover pathway. Plausible mechanism is proposed based on mechanistic investigations. Moreover, the reserved C - X bonds of these products are beneficial for performing further synthetic elaborations.
Abstract
Metallocenes are privileged backbones for synthesis and catalysis. However, the direct dehydrogenative C−H functionalization of unsymmetric metallocenes suffers from reactivity and ...selectivity issues. Herein, we report an electrochemically driven regioselective C−H phosphorylation of group 8 metallocenes. Mechanistic investigations indicate this dehydrogenative cross coupling occurs through an electrophilic radical substitution of the metallocene with a phosphoryl radical, facilitated by the metallocene itself. This work not only offers an efficient and divergent synthesis of phosphorylated metallocenes, but also provides a guide to interpret the reactivity and regioselectivity for the C−H functionalization of unsymmetric metallocenes.
A distinct copper-catalyzed boroacylation of allenes with acyl chlorides and bis(pinacolato)diboron is developed. For aromatic acyl chlorides, 1,2-boroacylation of allenes readily takes place, ...leading to the formation of tetrasubstituted vinylboronates with exclusive (
E
)-stereoselectivity. In comparison, the employment of alkyl acyl chlorides as electrophiles alters the selectivity to 2,3-boroacylated products. Additionally, the product can easily undergo Suzuki-Miyaura cross-coupling to afford tetrasubstituted alkene with complete retention of the configuration.
A copper-catalyzed boroacylation of allenes with acyl chlorides and bis(pinacolato)diboron is developed for the synthesis of diverse tetrasubstituted vinylboronates with exclusive (
E
)-stereoselectivity.
Amides have played a vital role in polymeric materials, natural products and pharmaceuticals. In recent years, transition metal catalyzed C−N bond formation reaction provides a reliable strategy for ...amides construction. Herein, we disclosed a photo‐induced electrophilic amidation reaction with N‐methoxyamides and arylboronic acids at low temperature using a simple iron salt as the catalyst precursor. Initial mechanistic studies suggested that crucial amide radical species was involved.
Inspired by recent transition‐metal catalyzed electrophilic amidations, we developed a photo‐induced electrophilic amidation of arylboronic acids with Fe catalyst to construct C−N bond. This protocol is also featured by its mild condition and broad substrate scope.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
A regiodivergent hydrophosphorylation of enynes with phosphites has been developed using earth-abundant nickel catalyst. The manipulation of regioselectivity can be achieved by regulating the ...insertion order of alkyne bonds with (RO)2P(O)–Ni–H or R2P(O)O–Ni–H species, respectively. Under the Ni/Xantphos catalysis, 4,1-hydrophosphorylation is selectively obtained while the adding of acid can promote reactions towards 1,2-addition. By employing an additional Pd–H catalysis, 2,1-hydrophosphorylation is also an accessible task in one-pot reaction. Mechanistic studies and analysis have also been performed to interpret the origin of the regioselective regulation. This work highlights the arts in accessing different regioisomers by diverting common elementary reaction steps.
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The Ni-catalyzed regiodivergent hydrophosphorylation of 1,3-enynes with phosphites has been developed through the regulation of common elementary reaction steps.
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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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