Solvent-Controlled, Tunable Domino Reaction of 3-Ylideneoxindoles with in Situ-Generated α-Aryldiazomethanes: A Facile Access to 3-Spirocyclopropyl-2-oxindole and Pyrazoloquinazolinone Scaffolds

Design, Development of Pyrazole-Linked Spirocyclopropyl Oxindole-Carboxamides as Potential Cytotoxic Agents and Type III Allosteric VEGFR-2 Inhibitors

Tumor progression depends on angiogenesis, which is stimulated by growth factors like VEGF, targeting VEGFR kinase with small molecules is an effective anti-angiogenic therapeutic approach. The rational modification of sunitinib (VEGFR-2 inhibitor) to spirocyclopropyloxindoline carboxamides have been performed and their in vitro cytotoxic profiling was evaluated. The molecular modelling studies enabled the screening of designed analogues and identifying the possible interactions within the type III allosteric inhibitor binding site of VEGFR-2. The biological screening of synthesized compounds 15 a-y, revealed the ability of compound 15 w to inhibit the cell growth in MCF-7 cell line with IC50 value of 3.87±0.19 μM and alongside inhibition of VEGFR-2 kinase at a IC50 concentration of 4.34±0.13 μM was observed. Also, VEGFR-2 inhibition was validated through HUVEC tube formation inhibition assay. The qualitative assessment of apoptosis induction by 15 w in MCF-7 cells was evaluated through staining studies such as AO/EB and DAPI staining, whereas quantification of apoptosis and cell cycle analysis were performed through FACS analysis. The metastatic ability of the cancer cells was evaluated through inhibition of cell migration by a scratch wound healing assay. The current study strives to sequentially optimize the structural attributes of the 3-alkenyl oxindole core to surpass the existing challenges of well-known VEGFR-2 inhibitors. The findings observed from this study highlights that compound 15 w to be a prominent lead towards the development of clinical drug candidates.

Leveraging in situ N-tosylhydrazones as diazo surrogates for efficient access to pyrazolo-[1,5-c]quinazolinone derivatives

We developed a transition metal-free methodology for the construction of pyrazoloquinazolinone derivatives. The strategy involves a one-pot reaction wherein the N-tosylhydrazone and its corresponding diazo derivative are generated in situ, followed by an intramolecular 1,3-dipolar cycloaddition-ring expansion to provide the pyrazolo-[1,5-c]quinazolinone motif. This approach enables straightforward access to a diverse range of highly functionalized N-heterocyclic compounds in good yields (up to 92%).

Quinazolines annelated at the N(3)-C(4) bond: Synthesis and biological activity

This review covers article and patent data obtained mostly within the period 2013-2023 on the synthesis and biological activity of quinazolines [c]-annelated by five- and six-membered heterocycles. Pyrazolo-, benzimidazo-, triazolo- and pyrimido- [c]quinazoline systems have shown multiple potential activities against numerous targets. We highlight that most research efforts are directed to design of anticancer and antibacterial agents of azolo[c]quinazoline nature. This review emphases both on the medicinal chemistry aspects of pyrrolo[c]-, azolo[c]- and azino[c]quinazolines and comprehensive synthetic strategies of quinazolines annelated at N(3)-C(4) bond in the perspective of drug development and discovery.

Diastereoselective Synthesis of Dihydrobenzofuran Spirooxindoles and Their Transformation into Benzofuroquinolinones by Ring Expansion of Oxindole Core

A mild and efficient approach for the diastereoselective synthesis of dihydrobenzofuran spirooxindoles using 3-chlorooxindoles and imines is presented. This process involves a formal [4 + 1] annulation, yielding the product with excellent diastereoselectivity. Furthermore, a novel method for constructing benzofuroquinolinone scaffolds through the ring expansion of oxindoles has been established. This method involves a lactam ring expansion to the quinolinone skeleton. Besides, a one-pot procedure for creating benzofuroquinolinone scaffolds from 3-chlorooxindoles and imines is also provided.

Design, Synthesis, Antitumour Evaluation, and In Silico Studies of Pyrazolo-[1,5-c]quinazolinone Derivatives Targeting Potential Cyclin-Dependent Kinases

An efficient, straightforward, and metal-free methodology to rapidly access functionalised pyrazolo-[1,5-c]quinazolinones via a [3 + 2] dipolar cycloaddition and regioselective ring expansion process was developed. The synthesised compounds were characterised by methods such as NMR, HRMS, and HPLC. The in vitro antiproliferative activity against A549 cells (non-small cell lung cancer) was significant for compounds 4i, 4m, and 4n with IC50 values of 17.0, 14.2, and 18.1 μM, respectively. In particular, compounds 4t and 4n showed inhibitory activity against CDK9/2. Predicted biological target and molecular modelling studies suggest that the compound 4t may target CDKs for antitumour effects. The synthesised derivatives were considered to have moderate drug-likeness and sufficient safety in silico. In summary, a series of pyrazolo-[1,5-c]quinazolinone derivatives with antitumour activity is reported for the first time. We provide not only a simple and efficient synthetic method but also helpful lead compounds for the further development of novel cyclin-dependent kinase (CDK) inhibitors.

Diastereoselective trans Cyclopropanation of 3-Alkylidene Oxindoles with In Situ Generated α-Diazo Carbonyls or α,β-Unsaturated Diazo Compounds

An efficient diastereoselective trans cyclopropanation of 3-alkylidene oxindoles with in situ generated α-diazo carbonyl compounds or α,β-unsaturated diazo compounds under metal-free conditions has been developed to synthesize 3-spirocyclopropyl-2-oxindole derivatives. The procedure is based on the 1,3-dipolar character of the corresponding diazo compounds under base-catalyzed conditions. The method has a wide substrate scope and uses easily available starting materials.

Stereoselective synthesis and applications of spirocyclic oxindoles

This review summaries recent synthetic developments towards spirocyclic oxindoles and applications as valuable medicinal and synthetic targets.

Synthesis of Spirocyclopropane Oxindoles via Michael-Initiated Cyclopropanation of Pyridinium Salts with 3-Ylidene Oxindoles

A Michael-initiated ring-closure reaction of pyridinium salts with arylidene oxindoles has been developed. A wide range of aryl-substituted spirocyclopropane oxindoles has been achieved in moderate to good yields (41–99%). This efficient strategy exhibits good functional group compatibility and may serve as an attractive method for the synthesis of diverse cyclopropanes.

Regioselective Ring Expansion of 3-Ylideneoxindoles with Tosyldiazomethane (TsDAM): A Metal-Free and Greener Approach for the Synthesis of Pyrazolo-[1,5-c]quinazolines

An efficient, metal-free approach to access pyrazolo-[1,5-c]quinazolines with 3-ylideneoxindoles and tosyldiazomethane (TsDAM) under mild aqueous reaction conditions has been developed and the solvent involvement in the present reaction has also been explored for the first time. This greener approach involves 1,3-dipolar cycloaddition, regioselective ring expansion, followed by the elimination of tosyl group with aqueous base in a single operation, and the product can be isolated in high purity without column chromatographic separation. The method is also compatible with a large variety of functional groups, providing good to excellent yields in water, thus resulting in a decrease of environmental impact in the pharmaceutical industry.

Regioselective ring expansion followed by H-shift of 3-ylidene oxindoles: a convenient synthesis of N-substituted/un-substituted pyrrolo[2,3-c] quinolines and marinoquinolines

Herein, we report a simple and metal-free protocol for the synthesis of 4-oxo-4,5-dihydro-3H-pyrrolo[2,3-c]quinolines. The present method under mild reaction conditions with wide functional group compatibility gives several unexplored N-substituted/unsubstituted 4-oxo-4,5-dihydro-3H-pyrrolo[2,3-c]quinolines and marinoquinolines in good to excellent yields. Mechanistic insights for the synthesis of N-substituted pyrroloquinolines reveal the ring expansion of 3-ylideneoxindoles and H-shift as the key steps.

Herein, we report a simple and metal-free protocol for the synthesis of 4-oxo-4,5-dihydro-3H-pyrrolo[2,3-c]quinolines.