The
free radical cyclization reaction is a promising strategy for
ring framework formation. Herein, we report a copper-catalyzed tandem
radical cyclization strategy for preparing substituted lactam derivatives.
This reaction proceeds through a radical coupling approach, which
not only allows a wide range of alkenes but also is quite compatible
with the primary, secondary, and tertiary radicals. In addition, density
functional theory calculations were performed to gain insights into
the reaction mechanism.
This report developed a method for the synthesis of C8-aminated pyrrolo-phenanthridines or -indoles by series ortho C(sp 2 )−H amination/ipso C(sp 2 )−H or C(sp 3 )−H arylation. Nbenzoyloxyamines, as electrophilic amination reagents, did not undergo an electrophilic substitution reaction with the pyrrole side, but they did undergo a site-selective C−H amination reaction with the benzene side via Pd/NBE catalysis. The C8-aminated pyrrolophenanthridines have strong fluorescence in solution and solid state. X-ray single crystal diffraction shows that the steric hindrance of amino and ortho benzene ring may inhibit aggregation-caused quenching (ACQ).
In
palladium/norbornene (Pd/NBE) chemistry, the “ortho effect” has been proven to be a key factor
in the process of β-carbon elimination to extrude NBE. Herein,
we found that the o-iodoaniline protected by a p-methoxybenzenesulfonyl group can recover the “ortho effect” and then undergo N–S bond cleavage
with vinyl palladium, thus achieving a highly selective C–N
coupling reaction in the Catallani–Lautens reaction system.
On the basis of this discovery, a one-step synthesis of highly functionalized
tricyclic indole derivatives was realized.
Carbazole, as one of the most important organic frameworks, has been used in optoelectronic materials and biochemistry. However, the synthesis of C4-substituted carbazole has always been an unsolved problem. This report describes the one-step synthesis of C4-aminated carbazoles and their derivatives through the series reaction of C−H amination and arylation. The substrate scope is wide. C4-Amino carbazoles substituted by C2, C6, C7, and C8 methyl groups, especially carbazole derivatives of fused rings, pyridine, and dibenzofuran, can be synthesized.
With the development of ortho C-H functionalization in Pd/NBE chemistry, the catalytic systems used are becoming increasingly complex. The increasingly complex catalytic systems may have created technical barri-ers for researchers in other fields to apply Pd/NBE chemical methods. This report describes the use of a simple Pd/NBE catalytic system to achieve ortho C-H oxylation and phosphonylation and other functionalization of iodobenzene through templated conversion reactions. The key point of this method is to explore the previous-ly unknown step of introducing dimethylamine in the ortho position of iodobenzene through C-H amination. Aryl dimethylamine is quickly converted to methyl quaternary ammonium salt precipitation, and methyl qua-ternary ammonium salt effectively avoids Hofmann elimination in the subsequent functionalization.
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