Palladium-Catalyzed CC Coupling of Aryl Halides with Isocyanides: An Alternative Method for the Stereoselective Synthesis of (3E)-(Imino)isoindolin-1-ones and (3E)-(Imino)thiaisoindoline 1,1-Dioxides

Palladium-Catalyzed Preparation of N-Substituted Benz[c,d]indol-2-imines and N-Substituted Amino-1-naphthylamides

Here, we report a novel and facile protocol for the synthesis of benz[c,d]indol-2-imines via palladium-catalyzed C-C and C-N coupling of 8-halo-1-naphthylamines with isocyanides in a single step. The reaction features broad substrate scopes and mild conditions, providing an efficient alternative for the construction of antiproliferative agents and BET bromodomain inhibitors. If 0.1 mL of H₂O was added to this reaction, the N-substituted amino-1-naphthylamides could be obtained easily.

Fluorescent annulated imidazo[4,5-c]isoquinolines via a GBB-3CR/imidoylation sequence - DNA-interactions in pUC-19 gel electrophoresis mobility shift assay

Herein we report the development of a sequential synthesis route towards annulated imidazo[4,5-c]isoquinolines comprising a GBB-3CR, followed by an intramolecular imidoylative cyclisation. X-Ray crystallography revealed a flat 3D structure of the obtained polyheterocycles. Thus, we evaluated their interactions with double-stranded DNA by establishing a pUC-19 plasmid-based gel electrophoresis mobility shift assay, revealing a stabilising effect on ds-DNA against strand-break inducing conditions.

Magnetic chitosan stabilized Cu(II)-tetrazole complex: an effective nanocatalyst for the synthesis of 3-imino-2-phenylisoindolin-1-one derivatives under ultrasound irradiation

In the present research, a recyclable catalyst has been prepared via a simple approach using chitosan as a linear polysaccharide. This paper reports the synthesis of novel copper(II) complex of 5-phenyl-1H-tetrazole immobilized on magnetic chitosan (MCS@PhTet@Cu(II)) as an effective catalyst. Transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), vibrating sample magnetometer (VSM), Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), and inductively coupled plasma mass spectrometry (ICP-MS) techniques were applied for the characterization of the catalyst. The catalytic activity of MCS@PhTet@Cu(II) was evaluated in the ultrasound-assisted synthesis of 3-imino-2-phenylisoindolin-1-one derivatives via the reaction between benzoyl chloride and arylcyanamides in ethanol at ambient temperature. Utilizing a wide variety of arylcyanamides under mild conditions, no use of toxic organic solvents, moderate reaction time, high yields along with catalyst excellent reusability and easy separation of the products without any tedious separation techniques, made this method a novel and simple process. The resulting heterogeneous catalyst showed valuable advantages such as easier work-up, better stability, and greater separation ability using an external magnet. The catalyst showed high efficacy and recyclability even after five cycles with no significant loss of its efficacy. The present methodology provides a path for the preparation of structurally diverse heterocyclic compounds, which may exhibit important biological activity.

Cobalt-Catalyzed Cyclization of 2-Bromobenzamides with Carbodiimides: A New Route for the Synthesis of 3-(Imino)isoindolin-1-ones

A novel synthetic pathway to approach 3-(imino)isoindolin-1-ones by the Co-catalyzed cyclization reaction of 2-bromobenzamides with carbodiimides has been developed. This catalytic reaction can tolerate a variety of substituents and provide corresponding products in moderate yields for most cases. According to the literature, the reaction mechanism is proposed through the formation of a five-membered aza-cobalacycle complex, which carries out the following reaction subsequence, including nucleophilic addition and substitution, to furnish the desired structures.

Three-Component Synthesis of Dibenzoxazepinamines and Dibenzothiazepinamines under Transition-Metal-Free Conditions

A convenient and efficient strategy for the synthesis of dibenzoxazepinamines and dibenzothiazepinamines has been developed. This three-component approach started from 2-nitrobenzaldehydes, 2-aminophenols, and methoxyammonium chlorides under metal-free conditions. The protocol has the advantages of readily available starting materials, simple and facile conditions, gram-scale synthesis, and broad substrate scope, providing an efficient and practical strategy for the preparation of potential drug-active dibenzoxazepinamines and dibenzothiazepinamines in one pot.

Access to 1-amino-3,4-dihydroisoquinolines via palladium-catalyzed C-H bond aminoimidoylation reaction from functionalized isocyanides

Efficient access to 1-amino-3,4-dihydroisoquinolines, through palladium-catalyzed intramolecular C-H bond aminoimidoylation of α-benzyl-α-isocyanoacetates, has been developed. Consecutive isocyanide insertion and C-H bond activation were realized with C-N and C-C bonds formation in one step under redox neutral conditions, employing O-benzoyl hydroxylamines as electrophilic amino sources.

Synthesis of 2,3-Difunctionalized Benzofuran Derivatives through Palladium-Catalyzed Double Isocyanide Insertion Reaction

A novel palladium-catalyzed tandem cyclization of 1-(allyloxy)-2-ethynylbenzene derivatives with isocyanides in the presence of water has been developed. The key intermediates, benzofuran-3-α-carbonyl aldehydes, were obtained through a simple acid hydrolysis process and could serve as precursors for structurally diverse 2,3-difunctionalized benzofuran derivatives such as important 2-benzofurylquinoxalines, benzofuran-3-α-ketoesters and benzofuryl ynediones. This transformation features convenient operation, simple and commercially available starting materials, broad functional-group compatibility, and moderate to good reaction yields.

Enantioselective Synthesis of Planar Chiral Pyridoferrocenes via Palladium-Catalyzed Imidoylative Cyclization Reactions

A highly efficient synthesis of planar chiral pyrido[3,4- b] ferrocenes by a palladium-catalyzed enantioselective isocyanide insertion/desymmetric C(sp²)-H bond activation reaction was developed. Various planar chiral pyridoferrocenes were obtained in high yields with good to excellent enantioselectivity under mild conditions (up to 99% yield, 99% ee), enabled by a unique SPINOL-derived phosphoramidite ligand.

Palladium-catalyzed β-selective C(sp2)–H carboxamidation of enamides by isocyanide insertion: synthesis of N-acyl enamine amides

An efficient synthesis of N-acyl enamine amides via palladium-catalyzed alkene C–H activation and isocyanide insertion has been developed.

Assembly of Polysubstituted Maleimides via Palladium-Catalyzed Cyclization Reaction of Alkynes with Isocyanides

An efficient and convenient palladium-catalyzed cyclization reaction of alkynes with isocyanides is described herein. This protocol allows the practical synthesis of many valuable polysubstituted maleimide derivatives after hydrolysis with a broad scope of substrates and mild reaction conditions. C-C, C═O, and C-N bonds were constructed in this transformation with isocyanide serving as both C and N sources.

Pd/Fe3O4 supported on nitrogen-doped reduced graphene oxide for room-temperature isocyanide insertion reactions

A versatile Pd/Fe₃O₄ supported on N-doped reduced graphene oxide (N-rGO) catalyst was developed to carry out the synthesis of quinazolinones and phenanthridines under extremely mild conditions through isocyanide insertion cascades.

Isocyanide-based multicomponent reactions in the synthesis of heterocycles

In this review, we update our previous presentation, underscoring the recent applications of isocyanides as privileged synthons in the synthesis of various heterocyclic compounds, especially focused on those synthesizedviamulticomponent reactions.

Palladium-catalyzed intramolecular C(sp(2))-H imidoylation for the synthesis of six-membered N-heterocycles

A new strategy for the construction of phenanthridine and isoquinoline scaffolds, starting from arenes containing a pending isocyanide moiety under palladium catalysis, has been developed. This process involves sequential intermolecular isocyanide insertion to an aryl palladium(II) intermediate and intramolecular aromatic C-H activation as key steps. Alkyl palladium(II) intermediate lacking β-hydrogen is also applicable to this reaction, generating unique bisheterocyclic scaffolds with three C-C bonds being formed consecutively.

Palladium-catalyzed imidoylative cyclization of α-isocyanoacetamides: efficient access to C2-diversified oxazoles

A novel procedure for the synthesis of C2-diversified oxazoles, through palladium-catalyzed imidoylative cyclization of α-isocyanoacetamides with aryl, vinyl, alkynyl halides, or triflates, was developed. Migratory insertion of isocyanide into a Csp3-palladium(II) intermediate in a cascade process was also realized, generating alkyl-substituted oxazoles. Therefore, oxazoles functionalized at the C2 position with sp, sp(2), and sp(3) hybridized carbon atoms are accessible by applying this method.

Palladium-catalyzed selective aminoamidation and aminocyanation of alkenes using isonitrile as amide and cyanide sources

An efficient aminoamidation and aminocyanation reaction of alkenes has been developed for the synthesis of substituted indolines, tetrahydroisoquinolines and pyrrolidines.

Synthesis of 6-aminophenanthridines via palladium-catalyzed insertion of isocyanides into N-sulfonyl-2-aminobiaryls

A robust route to a diverse set of 6-aminophenanthridines via palladium-catalyzed C–H activation of N-sulfonyl-2-aminobiaryl and isocyanide insertion is reported.

A room-temperature synthesis of 2,2′-bisoxazoles through palladium-catalyzed oxidative coupling of α-isocyanoacetamides

A novel one-step synthesis of both symmetric and unsymmetric 2,2′-bisoxazoles starting from simple acyclic α-isocyanoacetamides was achieved.

Palladium-catalyzed synthesis of 2-aminobenzoxazinones by aerobic oxidative coupling of anthranilic acids and isocyanides

Isocyanides have emerged as valuable C1 building blocks in palladium catalysis. Their potential has, however, mainly been exploited for the synthesis of amidines and amidine-containing heterocycles. To illustrate the broader applicability of isocyanides, we have recently developed a novel oxidative coupling of diamines and isocyanides furnishing valuable guanidine-containing heterocycles. We here report the extension of this protocol to the coupling of anthranilic acids and isocyanides leading to medicinally relevant 2-aminobenzoxazinones. This is a particularly challenging substrate class for this reaction due to the possibility of undesired decarboxylative pathways and the susceptibility of the products to nucleophilic attack. Therefore, this work underlines the generality and broad potential of the oxidative coupling of bisnucleophiles and isocyanides, facilitating the further implementation of this chemistry in library design.

Synthesis of 3-acyl-2-arylindole via palladium-catalyzed isocyanide insertion and oxypalladation of alkyne

The synthesis of 3-acyl-2-arylindole derivatives was performed through palladium-catalyzed isocyanide insertion and oxypalladation of an alkyne. As a result of the introduction of internal nucleophiles, domino cyclization was also achieved for the synthesis of several tetracyclic indole derivatives. Imidoylpalladium generated by isocyanide insertion is a key intermediate in these reactions.

Multicomponent synthesis of 4-aminophthalazin-1(2H)-ones by palladium-catalyzed isocyanide insertion

4-Aminophthalazin-1(2H)-ones (APOs) are underexplored heterocyclic compounds with promising and diverse biological activities. The classical synthesis of these compounds is tedious and does not allow the regioselective introduction of substituents. Here, we present our full studies on the Pd-catalyzed cross-coupling of substituted o-(pseudo)halobenzoates and hydrazines with isocyanide insertion allowing straightforward access to diversely substituted APOs. We illustrate the advantages of this method compared to other approaches and describe solutions for the limitations we encountered. In addition, we have developed efficient diversifications of this heterocyclic scaffold that allow access to more diverse APOs as well as novel heterocyclic scaffolds.

Palladium-catalyzed carbonylative Sonogashira coupling of aryl bromides via tert-butyl isocyanide insertion

A simple and efficient palladium-catalyzed carbonylative Sonogashira coupling via tert-butyl isocyanide insertion has been developed, which demonstrates the utility of isocyanides in intermolecular C-C bond construction. This methodology provides a novel pathway for the synthesis of alkynyl imines which can undergo simple silica gel catalyzed hydrolysis to afford alkynones. The approach is tolerant of a wide range of substrates and applicable to library synthesis.

Palladium-catalyzed synthesis of isocoumarins and phthalides via tert-butyl isocyanide insertion

A novel and highly efficient strategy for the synthesis of isocoumarins and phthalides through a palladium(0)-catalyzed reaction incorporating tert-butyl isocyanide has been developed. This process, providing one of the simplest methods for the synthesis of this class of valuable lactones, involves two steps including cyclization reaction and simple acid hydrolysis. The methodology is tolerant of a wide range of substrates and applicable to library synthesis.