An Efficient One-Pot Copper-Catalyzed Approach to Isoquinolin-1(2H)-one Derivatives

Access to Isoquinolin-2(1H)-yl-acetamides and Isoindolin-2-yl-acetamides from a Common MCR Precursor

We achieved a divergent synthesis of isoquinolin-2(1H)-yl-acetamides (16 examples, up to 90% yields) and regioselective isoindolin-2-yl-acetamides (14 examples, up to 93% yields) in moderate to good yields by reacting various substituted ethanones or terminal alkynes with Ugi-4CR intermediates via an ammonia-Ugi-4CR/Copper(I)-catalyzed annulation sequence reaction. The same intermediate thus gives 2D distant but 3D closely related scaffolds, which can be of high interest in exploiting chemistry space on a receptor. The scopes and limitations of these efficient sequence reactions are described, as well as gram-scale synthesis.

Synthesis of Imidazo[1,2-f]phenanthridines by Recyclable Magnetic MOF-Catalyzed Coupling and Cyclization of 2-(2-Bromoaryl)imidazoles with Cyclohexane-1,3-diones Followed by Aromatization

2-(2-Bromoaryl)imidazoles react with cyclohexane-1,3-diones in the presence of a catalytic amount of recyclable Fe₃O₄@SiO₂@MOF-199 and a base to give the corresponding C-C coupled and cyclized products 6,7-dihydroimidazo[1,2-f]phenanthridin-8(5H)-ones in high yields. The magnetic MOF catalyst could be easily recovered and reused four times without any significant loss of catalytic activity. The coupled and cyclized scaffolds were aromatized to imidazo[1,2-f]phenanthridines in high yields by a one-pot sequential procedure including reduction, dehydration, and oxidation. The present protocol could be applied to the synthesis of Zephycandidine A, which is known to exhibit anti-tumor activity.

CuCl2-catalyzed inexpensive, faster and ligand/additive free synthesis of isoquinolin-1(2H)-one derivatives via the coupling-cyclization strategy: Evaluation of a new class of compounds as potential PDE4 inhibitors

In spite of possessing a wide range of pharmacological properties the anti-inflammatory activities of isoquinolin-1(2H)-ones were rarely known or explored earlier. PDE4 inhibitors on the other hand in addition to their usefulness in treating inflammatory diseases have been suggested to attenuate the cytokine storm in COVID-19 especially TNF-α. In our effort, a new class of isoquinolin-1(2H)-ones derivatives containing an aminosulfonyl moiety were designed and explored as potential inhibitors of PDE4. Accordingly, for the first time a CuCl₂-catalyzed inexpensive, faster and ligand/additive free approach has been developed for the synthesis of these predesigned isoquinolin-1(2H)-one derivatives via the coupling-cyclization strategy. Thus, the CuCl₂-catalyzed reaction of 2-iodobenzamides with appropriate terminal alkynes proceeded with high chemo and regioselectivity affording the desired compounds in 77-84% yield within 1-1.5 h. The methodology also afforded simpler isoquinolin-1(2H)-ones devoid of aminosulfonyl moiety showing a broader generality and scope of this approach. Several of the synthesized compounds especially 3c, 3k and 3s showed impressive inhibition (83-90%) of PDE4B when tested at 10 µM in vitro whereas compounds devoid of aminosulfonyl moiety was found to be less active. In spite of high inhibition showed at 10 µM these compounds did not show proper concertation dependent inhibition below 1 µM that was reflected in their IC₅₀ values e.g. 2.43 ± 0.32, 3.26 ± 0.24 and 3.63 ± 0.80 µM for 3k, 3o and 3s respectively. The anti-inflammatory potential of these compounds was indicated by their TNF-α inhibition (60-50% at 10 µM). The in silico docking studies of these molecules suggested good interactions with PDE4B and selective inhibition of PDE4B by 3k over PDE4D that was supported by in vitro assay results. These observations together with the favorable ADME and safety predicted for 3kin silico not only suggested 3k as an interesting hit molecule for further studies but also reveal the first example of isoquinolin-1(2H)-one based inhibitor of PDE4B.

Cobalt-catalyzed coupling reactions of 2-halobenzamides with alkynes: investigation of ligand-controlled dual pathways

The Co-catalyzed reactions of 2-halobenzamides and alkynes to form quinolinones or 2-vinyl benzamides are described here. These two reactions can be controlled merely by ligands.

Gold/Lewis acid catalyzed oxidative cyclization involving activation of nitriles

A gold-catalyzed oxidative cyclization of alkyne-nitriles using water or alcohol as the external nucleophiles has been developed. The catalytic system, featured with gold and Lewis acid dual catalysis, allows a facile synthesis of functionalized isoquinolin-1(2H)-ones and 1-alkoxy-isoquinolines with a wide structural diversity.

Copper-catalyzed synthesis of 2-aminopyridylbenzoxazoles via domino reactions of intermolecular N-arylation and intramolecular O-arylation

A simple and general approach to nitrogen-containing heterocycles via copper-catalyzed domino reaction has been developed, and the corresponding 2-aminopyridylbenzoxazole derivatives were obtained in good to excellent yields using the readily available starting materials. This method possesses unique step economy features, and is of high tolerance towards various functional groups in the substrates.

Catalyst Controlled Divergent C4/C8 Site-Selective C-H Arylation of Isoquinolones

The catalyst-controlled C4/C8 site-selective C-H arylation of isoquinolones using aryliodonium salts as the coupling partners was developed. The C4-selective arylation was successfully achieved via an electrophilic palladation pathway. A completely different selectivity pattern was observed using an Ir(III) catalytic system, which resulted in C-C bond formation exclusively at the C8 position. The isoquinolone scaffold can be conveniently equipped with various aryl substituents at either the C4 or C8 position.

Regioselective synthesis of multisubstituted isoquinolones and pyridones via Rh(iii)-catalyzed annulation reactions

A mild and efficient Rh(iii)-catalyzed regioselective synthesis of isoquinolones and pyridones from N-methoxybenzamide or N-methoxymethacrylamide and diazo compounds has been developed, through tandem C–H activation, cyclization, and condensation.

Transition-metal-catalyzed intramolecular cyclization of amido(hetero)arylboronic acid aldehydes to isoquinolinones and derivatives

We report an innovative and simple three step high yielding synthesis of a library of 14 chiral isoquinolinone and azepinone derivatives with benzyl, pyridyl and thiophene cores starting from amidoarylboronic acid aldehydes.

A simple copper-catalyzed two-step one-pot synthesis of indolo[1,2-a]quinazoline

A convenient CuI/L-proline-catalyzed, two-step one-pot method has been developed for the preparation of indolo[1,2-a]quinazoline derivatives using a sequential Ullmann-type C–C and C–N coupling. This protocol provides an operationally simple and rapid strategy for preparing indolo[1,2-a]quinazoline derivatives and displays good functional group tolerance. All the starting materials are commercial available or can be easily prepared.

Heterogeneous Copper-Catalysed Cascade Reactions of 2-Bromobenzamides with β-Keto Esters Leading to Isoquinolin-1(2H)-One Derivatives

The heterogeneous copper-catalysed cascade reaction of 2-bromobenzamides with β-keto esters was achieved in dioxane at 80 °C in the presence of the MCM-41-immobilised bidentate nitrogen copper(I) complex [MCM-41-2N-CuI] with Cs2CO3 as base, affording a variety of isoquinolin-1(2 H)-one derivatives in moderate to good yields. This heterogeneous copper catalyst can be recovered by a simple filtration and reused 10 times without significant loss of activity.