3419-91-8

Usage

Abbreviation

PBI

Appearance

White to light yellow solid

Melting point

241-243°C

Type of compound

Heterocyclic compound

Usage in organic syntheses

Building block for the synthesis of various biologically active compounds

Usage in medicinal chemistry

Building block for the synthesis of various biologically active compounds

Potential applications

Optoelectronic devices, corrosion inhibitor

Chemical reactivity

Diverse

Structural properties

Unique, contributing to its potential in various applications

Upstream product

• 109-09-1 2-chloropyridine 
• 120-72-9 indole 
• 109-04-6 2-bromo-pyridine 
• 5029-67-4 2-iodopyridine 
• 271-26-1 3H-indole 
• 372-48-5 2-fluoropyridine 
• 61798-24-1 (1S,2S)-N,N'-dimethyl-1,2-diaminocyclohexane 
• 65185-58-2 2-(2-bromophenyl)ethanamine 
• 3770-50-1 2-carbethoxyindole 
• 1282034-09-6 2-pyridyl dimethylsulfamate 
• 98976-68-2 2-pyridyl N,N-diethylcarbamate 
• 142-08-5 2-hydroxypyridin 
• 496-15-1 1-indoline 
• 51-17-2 benzoimidazole 

Relevant academic research and scientific papers

Copper-Catalyzed Aerobic Oxidation of N-Pyridylindole Leading to Fused Quinazolinones

Copper catalyzed aerobic oxidation enables the tandem selective and efficient transformation of N-pyridylindole for the construction of 11H-pyrido[2,1-b]quinazolin-11-ones. The reaction shows good efficiency to accomplish the aerobic oxidation. Mechanisti

Transition-Metal-Free Synthesis of Fused Quinazolinones by Oxidative Cyclization of N-Pyridylindoles

An unprecedented synthesis of fused quinazolinones from N-pyridylindoles under oxidative conditions using a combination of (diacetoxyiodo)benzene and K2S2O8 is reported. The reaction is metal-free, has a broad substrate scope, is operationally simple with short reaction time, and provides 11H-pyrido[2,1-b]quinazolin-11-one derivatives in moderate to high yields. It is believed to proceed via an in situ generated 2-hydroxy-1-(pyridin-2-yl)indolin-3-one as the key reaction intermediate, which undergoes a C-C bond cleavage to produce an electrophilic C-3 site in N-pyridyl indole. Subsequent nucleophilic attack by pyridyl nitrogen results in its cyclization.

Elucidating the Mechanism of Aryl Aminations Mediated by NHC-Supported Nickel Complexes: Evidence for a Nonradical Ni(0)/Ni(II) Pathway

Nickel catalysis is gaining in popularity in recent years, mostly within the area of cross-coupling. However, unlike Pd, the mechanisms of Ni-catalyzed C-C and C-heteroatom bond forming reactions have been much less studied, in particular when N-heterocyclic carbenes are used as ligands. Here, we present a thorough study of the mechanism of C-N cross-coupling reactions catalyzed by an NHC-Ni complex. Focusing on the coupling of 2-chloropyridines with indole catalyzed by [(IPrNi(styrene)2] (IPr = N,N′-bis(2,6-diisopropylphenyl)imidazol-2-ylidene), we have examined each of the elementary steps: i.e., oxidative addition, ligand substitution, and reductive elimination. All relevant catalytic intermediates have been isolated and structurally characterized by both spectroscopic and crystallographic methods. Kinetic studies have revealed that the reductive elimination is the rate-limiting step. Catalyst deactivation is related to the formation of unproductive dinuclear pyridyl-bridged NHC-NiII species, which can be prevented by increasing the size of the heteroaryl chloride. These investigations support a neutral Ni(0)/Ni(II) catalytic cycle. Calculations corroborate the experimental evidence and confirm the influence exerted by the ligands in each of the elementary steps.

Ruthenium(II)-Catalyzed C-H Methylation with Trifluoroborates

A cationic ruthenium(II)-complex enabled unprecedented C-H methylations on indoles and pyrroles. The versatile catalyst proved to be widely applicable and delivered the methylated heteroarenes with excellent levels of positional selectivity and ample substrate scope. The robustness of the catalysts was reflected by the challenging racemization-free C-H methylation of (S)-tryptophan.

Controlling selectivity in N-heterocycle directed borylation of indoles

Electrophilic borylation of indoles with BX3(X = Cl or Br) using directing groups installed at N1 can proceed at the C2 or the C7 position. The six membered heterocycle directing groups utilised herein, pyridines and pyrimidine, result in indole C2 borylation being the dominant outcome (in the absence of a C2-substituent). In contrast, C7 borylation was achieved using five membered heterocycle directing groups, such as thiazole and benzoxazole. Calculations on the borylation of indole substituted with a five (thiazole) and a six (pyrimidine) membered heterocycle directing group indicated that borylation proceedsviaborenium cations with arenium cation formation having the highest barrier in both cases. The C7 borylated isomer was calculated to be the thermodynamically favoured product with both five and six membered heterocycle directing groups, but for pyrimidine directed indole borylation the C2 product was calculated to be the kinetic product. This is in contrast to thiazole directed indole borylation with BCl3where the C7 borylated isomer is the kinetic product too. Thus, heterocycle ring size is a useful way to control C2vs. C7 selectivity in N-heterocycle directed indole C-H borylation.

Rhodium-Catalyzed Additive-Free C?H Ethoxycarbonylation of (Hetero)Arenes with Diethyl Dicarbonate as a CO Surrogate

A rhodium-catalyzed C(sp2)-H ethoxycarbonylation of indoles and arylpyridines using diethyl dicarbonate was developed. The catalytic process features an additive-free ethoxycarbonylation reaction, in which only ethanol and CO2 are produced as byproducts, providing a CO-free and operationally simple protocol. The introduced ethoxycarbonyl group is easily transformed into other ester and amide functionalities in a single step. Moreover, the reaction can be successfully applied on gram scale, and allows for the efficient synthesis of indole-2-carboxylic acid esters and isophthalates.

Functionalization of superparamagnetic Fe3O4@SiO2 nanoparticles with a Cu(II) binuclear Schiff base complex as an efficient and reusable nanomagnetic catalyst for N-arylation of α-amino acids and nitrogen-containing heterocycles with aryl halides

Fe3O4@SiO2 nanoparticles was functionalized with a binuclear Schiff base Cu(II)-complex (Fe3O4@SiO2/Schiff base-Cu(II) NPs) and used as an effective magnetic hetereogeneous nanocatalyst for the N-arylation of α-amino acids and nitrogen-containig heterocycles. The catalyst, Fe3O4@SiO2/Schiff base-Cu(II) NPs, was characterized by Fourier transform infrared (FTIR) and ultraviolet-visible (UV-vis) analyses step by step. Size, morphology, and size distribution of the nanocatalyst were studied by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and dynamic light scatterings (DLS) analyses, respectively. The structure of Fe3O4 nanoparticles was checked by X-ray diffraction (XRD) technique. Furthermore, the magnetic properties of the nanocatalyst were investigated by vibrating sample magnetometer (VSM) analysis. Loading content as well as leaching amounts of copper supported by the catalyst was measured by inductive coupled plasma (ICP) analysis. Also, thermal studies of the nanocatalyst was studied by thermal gravimetric analysis (TGA) instrument. X-ray photoelectron spectroscopy (XPS) analysis of the catalyst revealed that the copper sites are in +2 oxidation state. The Fe3O4@SiO2/Schiff base-Cu(II) complex was found to be an effective catalyst for C–N cross-coupling reactions, which high to excellent yields were achieved for α-amino acids as well as N-hetereocyclic compounds. Easy recoverability of the catalyst by an external magnet, reusability up to eight runs without significant loss of activity, and its well stability during the reaction are among the other highlights of this catalyst.

Cp?Co(III)-Catalyzed enantioselective hydroarylation of unactivated terminal alkenes via C-H activation

Enantioselective hydroarylation of unactivated terminal akenes constitutes a prominent challenge in organic chemistry. Herein, we reported a Cp*Co(III)-catalyzed asymmetric hydroarylation of unactivated aliphatic terminal alkenes assisted by a new type of tailor-made amino acid ligands. Critical to the chiral induction was the engaging of a novel noncovalent interaction (NCI), which has seldomly been disclosed in the C-H activation area, arising from the molecular recognition among the organocobalt(III) intermediate, the coordinated alkene, and the well-designed chiral ligand. A broad range of C2-alkylated indoles were obtained in high yields and excellent enantioselectivities. DFT calculations revealed the reaction mechanism and elucidated the origins of chiral induction in the stereodetermining alkene insertion step.

Iminyl-radicals by electrochemical decarboxylation of α-imino-oxy acids: construction of indole-fused polycyclics

Iminyl radicals are reactive intermediates that can be used for the construction of various valuable heterocycles. Herein, the electrochemical decarboxylation of α-imino-oxy acids for the generation of iminyl radicals has been accomplished under exogenous-oxidant- and metal-free conditions through the use ofnBu4NBr as a mediator. The resulting iminyl radicals undergo intramolecular cyclization smoothly with the adjacent (hetero)arenes to afford a series of indole-fused polycyclic compounds.

N-substituted aminobiphenyl palladacycles stabilized by dialkylterphenyl phosphanes: Preparation and applications in C[sbnd]N cross-coupling reactions

Neutral and cationic N-methyl- and N-phenyl-2-aminobiphenyl methanesulfonate palladacycles stabilized with dialkylterphenyl phosphanes have been prepared and characterized. Neutral structures are favored with the less bulky phosphane PMe2ArXyl2, L1, while more sterically demanding ligands PiPr2ArXyl2, L3, and PCyp2ArXyl2 (Cyp = cyclopentyl), L4, lead to cationic complexes in which the phosphane exhibits a bidentate κ1-P, η1-Carene coordination mode involving one of the ipso carbon atoms of a flanking terphenyl aryl ring. The complexes were evaluated for activity in C[sbnd]N cross-coupling reactions and [Pd(N-methyl-2-aminobiphenyl)L4](OMs) (OMs = mesylate) was identified as the most efficient precatalyst, facilitating the coupling of aryl chlorides with secondary and primary amines and indoles.