Access to the Cinnoline Scaffold via Rhodium-Catalyzed Intermolecular Cyclization under Mild Conditions

Rh(III)-Catalyzed N-Amino-Directed C-H Coupling with 3-Methyleneoxetan-2-ones for 1,2-Dihydroquinoline-3-carboxylic Acid Synthesis

Dynamic polarity analysis is proposed herein as a general tool for investigating static polarity and transient polarity and revealing expanded reactivity patterns. Through this analysis formalism, polarity matching has been established for Rh(III)-catalyzed N-amino-directed C-H coupling with 3-methyleneoxetan-2-ones, providing efficient access to 1,2-dihydroquinoline-3-carboxylic acids. The identified reaction, by virtue of the internal oxidative mechanism, showcases mild reaction conditions (room temperature), a short reaction time (2 h), and a generally high product yield.

Efficient method for the synthesis of novel methyl 4-cinnolinecarboxylate

A new method is designed for the synthesis of some novel methyl 3-aryl/alkyl-4-cinnolinecarboxylate with developed a general Richter cyclization through diazotization strategy of commercially available 2-aryl/alkyl ethynyl aniline and methyl acetate. Most substrates were achieved in moderate to excellent yields in one-pot procedures under mild reaction conditions.

Synthesis of Tetrahydrocarbazol-4-ones via Rh(III)-Catalyzed C-H Activation/Annulation of Arylhydrazines with Iodonium Ylides

The rhodium(III)-catalyzed C-H activation followed by intramolecular annulation reactions between arylhydrazines and iodonium ylides under suitable conditions has been described. Tetrahydrocarbazol-4-ones are readily achieved with moderate to excellent yields. The synthetic protocol features a wide range of substrates with high functional group tolerance. The gram-scale reaction and derivatization of the product demonstrate the synthetic practicality and utilization of this method.

New synthesis of a late-stage tetracyclic key intermediate of lumateperone

New approaches have been tested for the synthesis of lumateperone intermediates. As a result of these efforts, a novel synthesis of the late-stage tetracyclic key intermediate of lumateperone starting from the commercially available quinoxaline is described. The tetracyclic skeleton was constructed by the reaction of 1-trifluoroacetyl-4-aminoquinoxaline with ethyl 4-oxopiperidine-1-carboxylate in a Fischer indole synthesis. The inexpensive starting material, the efficient synthetic steps, and the avoidance of the borane-based reduction step provide a reasonable potential for scalability.

Recent developments in the green synthesis of biologically relevant cinnolines and phthalazines

Both cinnolines and phthalazines are heterocyclic compounds which have a wide range of biological activities and pharmacological profiles. This work represents the recent advances in the green synthesis of cinnolines and phthalazines as 1,2 and 2,3-diazanaphalenes were cited. The docking studies and mode of action for key scaffolds were also reported.

Hydrazine-Directed Rh(III) Catalyzed (4+2) Annulation with Sulfoxonium Ylides: Synthesis and Photophysical Properties of Dihydrocinnolines

We herein report hydrazine-directed, Rh(III) catalyzed (4+2) annulation of N-alkyl aryl hydrazines with sulfoxonium ylides as a safe carbene precursor. The reaction shows excellent functional group tolerance with broad substrate...

Transition-Metal-Catalyzed C-H Bond Functionalization of Arenes/Heteroarenes via Tandem C-H Activation and Subsequent Carbene Migratory Insertion Strategy

The past decade has witnessed tremendous developments in transition-metal-catalyzed C-H bond activation and subsequent carbene migratory insertion reactions, thus assisting in the construction of diverse arene/heteroarene scaffolds. Various transition-metal catalysts serve this purpose and provide efficient pathways for an easy access to substituted heterocycles. A brief introduction to metal-carbenes has been provided along with key mechanistic pathways underlying the coupling reactions. The purpose of this review is to provide a concise knowledge about diverse directing group-assisted coupling of varied arenes/heteroarenes and acceptor-acceptor/donor-acceptor diazo compounds. The review also highlights the synthesis of various carbocycles and fused heterocycles through diazo insertion pathways, via C-C, C-N and C-O bond forming reactions. The mechanism usually involves a C-H activation process, followed by diazo insertion leading to subsequent coupling.

RhIII-Catalyzed formal [5 + 1] cyclization of 2-pyrrolyl/indolylanilines using vinylene carbonate as a C1 synthon

A rhodium(iii)-catalyzed formal C–H [5 + 1] cyclization of 2-pyrrolyl/indolylanilines with vinylene carbonate has been explored towards the potent assembly of diverse 4-methylpyrrolo[1,2-a]quinoxalines.

A direct synthesis method towards spirocyclic indazole derivatives via Rh(iii)-catalyzed C–H activation and spiroannulation

A rhodium(iii)-catalyzed [4 + 1] spiroannulation of N-aryl phthalazine-diones (pyridazine-diones) with diazo compounds to construct spirocyclic indazole derivatives with diverse structures is described.

N-Trifluoromethyl Hydrazines, Indoles and Their Derivatives

Reported herein is the first efficient strategy to synthesize a broad range of unsymmetrical N-CF₃ hydrazines, which served as platform to unlock numerous currently inaccessible derivatives, such as tri- and tetra-substituted N-CF₃ hydrazines, hydrazones, sulfonyl hydrazines, and valuable N-CF₃ indoles. These compounds proved to be remarkably robust, being compatible with acids, bases, and a wide range of synthetic manipulations. The feasibility of RN(CF₃ )-NH₂ to function as a directing group in C-H functionalization is also showcased.

Rh(iii)-catalyzed, hydrazine-directed C–H functionalization with 1-alkynylcyclobutanols: a new strategy for 1H-indazoles

Rh(iii)-catalyzed coupling of phenylhydrazines with 1-alkynylcyclobutanols was realized through a hydrazine-directed C–H functionalization and [4+1] annulation pathway.

Ir(iii)-Catalyzed direct C–H functionalization of N-phenylacetamide with α-diazo quinones: a novel strategy for producing 2-hydroxy-2′-amino-1,2′-biaryl scaffolds

A novel strategy is reported for the construction of 2-hydroxy-2′-amino-1,1′-biaryl scaffolds via Ir(iii)-catalyzed direct C–H bond activation under mild reaction conditions.

Spiro[indene-1,4'-oxa-zolidinones] Synthesis via Rh(III)-Catalyzed Coupling of 4-Phenyl-1,3-oxazol-2(3H)-ones with Alkynes: A Redox-Neutral Approach

Transition-metal-catalyzed C-H activation synthesis of heterocyclic spiro[4,4]nonanes has persistently witnessed the use of additional stoichiometric transition-metal oxidant when employing C═C bond as the spiro ring closure site. Herein, we have addressed the issue by reporting a redox-neutral strategy for spiro[indene-1,4'-oxa-zolidinones] synthesis via Rh(III)-catalyzed coupling of 4-phenyl-1,3-oxazol-2(3H)-ones with alkynes. The synthesis features a broad substrate scope and high regiospecificity.

Ruthenium(ii)-catalyzed synthesis of indazolone-fused cinnolines via C-H coupling with diazo compounds

A robust, efficient and scalable method for the synthesis of 12H-indazolo[2,1-a]cinnolin-12-ones was developed. Significantly, a less developed cationic complex [Ru(p-cymene)(MeCN)3(SbF6)2] was found to be effective for this transformation. In this reaction, a tandem pathway of C-H ruthenation, Ru(ii)-carbene formation, migratory insertion and condensation was involved. The results of a primary mechanistic study suggested that the C-H activation process might follow an electrophilic-type metalation/deprotonation mechanism.

Rhodium-catalyzed oxidative C–H/C–H cross-coupling of aniline with heteroarene: N-nitroso group enabled mild conditions

A rhodium(iii)-catalyzed oxidative ortho-heteroarylation of N-nitrosoaniline with heteroarene has been developed for the synthesis of (2-aminophenyl)heteroaryls under mild conditions.

Rhodium-catalyzed malonation of 2-arylquinazolines with 2-diazomalonates: double C–H functionalization

Herein, rhodium-catalyzed malonation of 2-arylquinazolines with diazomalonates was described.

Regio-selective synthesis of diversely substituted benzo[a]carbazoles through Rh(iii)-catalyzed annulation of 2-arylindoles with α-diazo carbonyl compounds

A novel synthetic approach toward benzo[a]carbazoles and 6-aminobenzo[a]carbazoles containing an unprotected NH unit through Rh(iii)-catalyzed cascade reactions of 2-arylindoles or 2-arylindole-3-carbonitriles with α-diazo carbonyl compounds is presented.

Iridium catalyzed acceptor/acceptor carbene insertion into N–H bonds in water

Carbenes from highly stable acceptor/acceptor diazo compounds can be inserted into the N–H bonds of aromatic amines using an Ir(i) catalyst in an aqueous medium.

Rh(iii)-catalyzed sequential C–H activation and annulation: access to N-fused heterocycles from arylazoles and α-diazocarbonyl compounds

Valuable N-fused heterocycles were successfully obtained via Rh(iii)-catalyzed sequential C–H activation and annulation.

Bidentate Directing-Enabled, Traceless Heterocycle Synthesis: Cobalt-Catalyzed Access to Isoquinolines

Traceless heterocycle synthesis based on transition-metal-catalyzed C-H functionalization is synthetically appealing but has been realized only in monodentate directing systems. Bidentate directing systems allow for the achievement of high catalytic reactivity without the need for a high-cost privileged ligand. The first bidentate directing-enabled, traceless heterocycle synthesis is demonstrated in the cobalt-catalyzed synthesis of isoquinolines via 2-hydrazinylpyridine-directed C-H coupling/cyclization with alkynes. Convenient directing group installation through a ubiquitously present ketone group allows synthetic elaboration for complex molecules.

Rhodium-catalyzed C–H activation of 3-(indolin-1-yl)-3-oxopropanenitriles with diazo compounds and tandem cyclization leading to hydrogenated azepino[3,2,1-hi]indoles

Rh(iii)-Catalyzed C–H activation of 3-(indolin-1-yl)-3-oxopropanenitriles with diazo compounds and tandem cyclization leading to seven-membered ring scaffolds has been developed.