Isoquinolin-1-one inhibitors of the MDM2-p53 interaction

Rational Design, Synthesis, Separation, and Characterization of New Spiroxindoles Combined with Benzimidazole Scaffold as an MDM2 Inhibitor

Rational design for a new spiroxindoles, combined with a benzimidazole scaffold to identify a new murine double minute two (MDM2) inhibitor was synthesized and characterized. The desired spiroxindoles were achieved via a [3+2] cycloaddition reaction approach which afforded the cycloadducts with four asymmetric centers separated in an excellent regioselective and diastereoselective compound. The separated spiroxindoles were subjected to a set of biochemical assays including an NCI cell panel assay, MTT assay, and MDM2 binding analysis by a microscale thermophoresis assay. The anticancer reactivity for the tested compounds showed IC50 (µM) in the range between 3.797–6.879 µM, and compound 7d with IC50 = 3.797 ± 0.205 µM was the most active candidate between the series. The results showed promising results that identified that compound 7a could be inhibited the MDM2 with KD = 2.38 μm. Compound 7a developed a network of interactions with the MDM2 receptor studied in silico by molecular docking.

Synthesis of Novel 1-Oxo-2,3,4-trisubstituted Tetrahydroisoquinoline Derivatives, Bearing Other Heterocyclic Moieties and Comparative Preliminary Study of Anti-Coronavirus Activity of Selected Compounds

A series of novel 1-oxo-2,3,4-trisubstituted tetrahydroisoquinoline (THIQ) derivatives bearing other heterocyclic moieties in their structure were synthesized based on the reaction between homophthalic anhydride and imines. Initial studies were carried out to establish the anti-coronavirus activity of some of the newly obtained THIQ-derivatives against two strains of human coronavirus-229E and OC-43. Their antiviral activity was compared with that of their close analogues, piperidinones and thiomorpholinones, previously synthesized in our group, with aim to expand the range of the tested representative sample and to obtain valuable preliminary information about biological properties of a wider variety of compounds.

Synthesis and Biological Evaluation of Novel Synthetic Indolone Derivatives as Anti-Tumor Agents Targeting p53-MDM2 and p53-MDMX

A series of novel indolone derivatives were synthesized and evaluated for their binding affinities toward MDM2 and MDMX. Some compounds showed potent MDM2 and moderate MDMX activities. Among them, compound A13 exhibited the most potent affinity toward MDM2 and MDMX, with a K_i of 0.031 and 7.24 μM, respectively. A13 was also the most potent agent against HCT116, MCF7, and A549, with IC₅₀ values of 6.17, 11.21, and 12.49 μM, respectively. Western blot analysis confirmed that A13 upregulated the expression of MDM2, MDMX, and p53 by Western blot analysis. These results indicate that A13 is a potent dual p53-MDM2 and p53-MDMX inhibitor and deserves further investigation.

Ligand-Based and Docking-Based Virtual Screening of MDM2 Inhibitors as Potent Anticancer Agents

A ligand-based and docking-based virtual screening was carried out to identify novel MDM2 inhibitors. A pharmacophore model with four features was used for virtual screening, followed by molecular docking. Seventeen compounds were selected for an in vitro MDM2 inhibition assay, and compounds AO-476/43250177, AG-690/37072075, AK-968/15254441, AO-022/43452814, and AF-399/25108021 showed promising MDM2 inhibition activities with K_i values of 9.5, 8.5, 23.4, 3.2, and 23.1 μM, respectively. Four compounds also showed antiproliferative activity, and compound AO-022/43452814 was the most potent hit with IC₅₀ values of 19.35, 26.73, 12.63, and 24.14 μM against MCF7 (p53 +/+), MCF7 (p53 -/-), HCT116 (p53 +/+), and HCT116 (p53 -/-) cell lines, respectively. Compound AO-022/43452814 could be used as a scaffold for the development of anticancer agents targeting MDM2.

Competition NMR for Detection of Hit/Lead Inhibitors of Protein-Protein Interactions

Screening for small-molecule fragments that can lead to potent inhibitors of protein–protein interactions (PPIs) is often a laborious step as the fragments cannot dissociate the targeted PPI due to their low μM–mM affinities. Here, we describe an NMR competition assay called w-AIDA-NMR (weak-antagonist induced dissociation assay-NMR), which is sensitive to weak μM–mM ligand–protein interactions and which can be used in initial fragment screening campaigns. By introducing point mutations in the complex’s protein that is not targeted by the inhibitor, we lower the effective affinity of the complex, allowing for short fragments to dissociate the complex. We illustrate the method with the compounds that block the Mdm2/X-p53 and PD-1/PD-L1 oncogenic interactions. Targeting the PD-/PD-L1 PPI has profoundly advanced the treatment of different types of cancers.

Synthesis of DNA-coupled isoquinolones and pyrrolidines by solid phase ytterbium- and silver-mediated imine chemistry

DNA-encoded libraries of chemically synthesized compounds are an important small molecule screening technology. The synthesis of encoded compounds in solution is currently restricted to a few DNA-compatible and water-tolerant reactions. Encoded compound synthesis of short DNA-barcodes covalently connected to solid supports benefits from a broad range of choices of organic solvents. Here, we show that this encoded chemistry approach allows for the synthesis of DNA-coupled isoquinolones by an Yb(iii)-mediated Castagnoli-Cushman reaction under anhydrous reaction conditions and for the synthesis of highly substituted pyrrolidines by Ag(i)-mediated 1,3-dipolar azomethine ylide cycloaddition. An encoding scheme for these DNA-barcoded compounds based on a DNA hairpin is demonstrated.

The MDM2/MDMX-p53 Antagonist PM2 Radiosensitizes Wild-Type p53 Tumors

Radiotherapy amplifies p53 expression in cancer cells with wild-type (wt) p53. Blocking the negative regulators MDM2 and MDMX stabilizes p53 and may therefore potentiate radiotherapy outcomes. In this study, we investigate the efficacy of the novel anti-MDM2/X stapled peptide PM2 alone and in combination with external gamma radiation in vitro and in vivo PM2 therapy combined with radiotherapy elicited synergistic therapeutic effects compared with monotherapy in cells with wt p53 in both in vitro and in vivo assays, whereas these effects did not manifest in p53 ^-/- cells. Biodistribution and autoradiography of ¹²⁵I-PM2 revealed high and retained uptake homogenously distributed throughout the tumor. In mice carrying wt p53 tumors, PM2 combined with radiotherapy significantly prolonged the median survival by 50%, whereas effects of PM2 therapy on mutant and p53 ^-/- tumors were negligible. PM2-dependent stabilization of p53 was confirmed with ex vivo immunohistochemistry. These data demonstrate the potential of the stapled peptide PM2 as a radiotherapy potentiator in vivo and suggest that clinical application of PM2 with radiotherapy in wt p53 cancers might improve tumor control.Significance: These findings contribute advances to cancer radiotherapy by using novel p53-reactivating stapled peptides as radiosensitizers in wild-type p53 cancers. Cancer Res; 78(17); 5084-93. ©2018 AACR.

A speedy route to sterically encumbered, benzene-fused derivatives of privileged, naturally occurring hexahydropyrrolo[1,2-b]isoquinoline

A series of 15 benzene-fused hexahydropyrrolo[1,2-b]isoquinolonic acids with substantial degree of steric encumbrance has been prepared via a novel variant of the Castagnoli–Cushman reaction of homophthalic anhydride (HPA) and various indolenines. The employment of a special kind of a cyclic imine component reaction allowed, for the first time, isolating a Mannich-type adduct between HPA and an imine component which has been postulated but never obtained in similar reactions.

Stereoselective Synthesis of Quaternary Pyrrolidine-2,3-diones and β-Amino Acids

A facile, diastereoselective synthesis of highly substituted pyrrolidine-2,3-diones is reported, along with the one-step conversion of these heterocycles to novel β-amino acids and further functionalized derivatives. This method involves an unusually mild, one-pot, three-component cyclization/allylation followed by a Claisen rearrangement to provide unusual pyrrolidinone products that are densely functionalized and contain an all-carbon quaternary stereocenter. The reported reaction sequence is operationally simple, exquisitely diastereoselective, and provides gram-scale access to valuable heterocyclic scaffolds and β-amino acids not readily accessible via existing approaches.

Discovery of Novel Spiro[3H-indole-3,2'-pyrrolidin]-2(1H)-one Compounds as Chemically Stable and Orally Active Inhibitors of the MDM2-p53 Interaction

Scaffold modification based on Wang's pioneering MDM2-p53 inhibitors led to novel, chemically stable spiro-oxindole compounds bearing a spiro[3H-indole-3,2'-pyrrolidin]-2(1H)-one scaffold that are not prone to epimerization as observed for the initial spiro[3H-indole-3,3'-pyrrolidin]-2(1H)-one scaffold. Further structure-based optimization inspired by natural product architectures led to a complex fused ring system ideally suited to bind to the MDM2 protein and to interrupt its protein-protein interaction (PPI) with TP53. The compounds are highly selective and show in vivo efficacy in a SJSA-1 xenograft model even when given as a single dose as demonstrated for 4-[(3S,3'S,3'aS,5'R,6'aS)-6-chloro-3'-(3-chloro-2-fluorophenyl)-1'-(cyclopropylmethyl)-2-oxo-1,2,3',3'a,4',5',6',6'a-octahydro-1'H-spiro[indole-3,2'-pyrrolo[3,2-b]pyrrole]-5'-yl]benzoic acid (BI-0252).

Medicinal Chemistry Strategies to Disrupt the p53-MDM2/MDMX Interaction

The growth inhibitory activity of p53 tumor suppressor is tightly regulated by interaction with two negative regulatory proteins, murine double minute 2 (MDM2) and X (MDMX), which are overexpressed in about half of all human tumors. The elucidation of crystallographic structures of MDM2/MDMX complexes with p53 has been pivotal for the identification of several classes of inhibitors of the p53-MDM2/MDMX interaction. The present review provides in silico strategies and screening approaches used in drug discovery as well as an overview of the most relevant classes of small-molecule inhibitors of the p53-MDM2/MDMX interaction, their progress in pipeline, and highlights particularities of each class of inhibitors. Most of the progress made with high-throughput screening has led to the development of inhibitors belonging to the cis-imidazoline, piperidinone, and spiro-oxindole series. However, novel potent and selective classes of inhibitors of the p53-MDM2 interaction with promising antitumor activity are emerging. Even with the discovery of the 3D structure of complex p53-MDMX, only two small molecules were reported as selective p53-MDMX antagonists, WK298 and SJ-172550. Dual inhibition of the p53-MDM2/MDMX interaction has shown to be an alternative approach since it results in full activation of the p53-dependent pathway. The knowledge of structural requirements crucial to the development of small-molecule inhibitors of the p53-MDMs interactions has enabled the identification of novel antitumor agents with improved in vivo efficacy.

Unveiling the "Three-Finger Pharmacophore" Required for p53-MDM2 Inhibition by Saturation-Transfer Difference (STD) NMR Initial Growth-Rates Approach

Inhibitors of the p53-MDM2 protein-protein interaction are emerging as a new and validated approach to treating cancer. Herein, we describe the synthesis and inhibitory evaluation of a series of isoquinolin-1-one analogues, and highlight the utility of an initial growth-rates saturation-transfer difference (STD) NMR approach supported by protein-ligand docking to investigate p53-MDM2 inhibition. The approach is illustrated by the study of compound 1, providing key insights into the binding mode of this kind of MDM2 ligands and, more importantly, readily unveiling the previously proposed three-finger pharmacophore requirement for p53-MDM2 inhibition.

Fragment-based library generation for the discovery of a peptidomimetic p53-Mdm4 inhibitor

On the basis of our recently resolved first cocrystal structure of Mdm4 in complex with a small molecule inhibitor (PDB ID 3LBJ ), we devised an approach for the generation of potential Mdm4 selective ligands. We performed the Ugi four-component reaction (Ugi-4CR) in 96-well plates with an indole fragment, which is specially designed to mimic Trp23, a key amino acid for the interaction between p53 and Mdm4. Generally the reaction yielded mostly precipitates collected by 96-well filter plates. The best hit compound was found to be active and selective for Mdm4 (Ki=5 μM, 10-fold stronger than Mdm2). This initial hit may serve as the starting point for designing selective p53-Mdm4 inhibitor with higher affinity.

The MDM2-p53 pathway revisited

The p53 tumor suppressor is a key transcription factor regulating cellular pathways such as DNA repair, cell cycle, apoptosis, angiogenesis, and senescence. It acts as an important defense mechanism against cancer onset and progression, and is negatively regulated by interaction with the oncoprotein MDM2. In human cancers, the TP53 gene is frequently mutated or deleted, or the wild-type p53 function is inhibited by high levels of MDM2, leading to downregulation of tumor suppressive p53 pathways. Thus, the inhibition of MDM2-p53 interaction presents an appealing therapeutic strategy for the treatment of cancer. However, recent studies have revealed the MDM2-p53 interaction to be more complex involving multiple levels of regulation by numerous cellular proteins and epigenetic mechanisms, making it imperative to reexamine this intricate interplay from a holistic viewpoint. This review aims to highlight the multifaceted network of molecules regulating the MDM2-p53 axis to better understand the pathway and exploit it for anticancer therapy.

Radiosensitization of wildtype p53 cancer cells by the MDM2-inhibitor PXN727 is associated with altered heat shock protein 70 (Hsp70) levels

The oncoprotein MDM2 (murine double minute 2) is often overexpressed in human tumors and thereby attenuates the function of the tumor suppressor p53. In this study, we investigated the effects of the novel MDM2-inhibitor PXN727 on p53 activation, cell proliferation, cell cycle distribution and radiosensitivity. Since the localization of heat shock protein 70 (Hsp70) exerts different effects on radioresistance of tumor cells, we investigated the impact of PXN727 on intracellular, membrane, and secreted Hsp70 levels. We could show that PXN727 exerts its effects on wildtype p53 (HCT116 p53⁺/⁺, A549) but not p53 depleted (HCT116 p53⁻/⁻) or mutated (FaDu) tumor cells. PXN727 activates p53, induces the expression of p21, reduces the proportion of cells in the radioresistant S-phase and induces senescence. Radiosensitivity was significantly increased by PXN727 in HCT116 p53⁺/⁺ tumor cells. Furthermore, PXN727 causes a downregulation of Hsp70 membrane expression and an upregulated secretion of Hsp70 in wildtype p53 tumor cells. Our data suggest that re-activation of p53 by MDM2-inhibition modulates Hsp70 membrane expression and secretion which might contribute to the radiosensitizing effect of the MDM2-inhibitor PXN727.

Enabling large-scale design, synthesis and validation of small molecule protein-protein antagonists

Although there is no shortage of potential drug targets, there are only a handful known low-molecular-weight inhibitors of protein-protein interactions (PPIs). One problem is that current efforts are dominated by low-yield high-throughput screening, whose rigid framework is not suitable for the diverse chemotypes present in PPIs. Here, we developed a novel pharmacophore-based interactive screening technology that builds on the role anchor residues, or deeply buried hot spots, have in PPIs, and redesigns these entry points with anchor-biased virtual multicomponent reactions, delivering tens of millions of readily synthesizable novel compounds. Application of this approach to the MDM2/p53 cancer target led to high hit rates, resulting in a large and diverse set of confirmed inhibitors, and co-crystal structures validate the designed compounds. Our unique open-access technology promises to expand chemical space and the exploration of the human interactome by leveraging in-house small-scale assays and user-friendly chemistry to rationally design ligands for PPIs with known structure.

Inhibitors of MDM2 and MDMX: a structural perspective

p53 is a potent tumor suppressor with a crucial role in preventing uncontrolled cell proliferation and is therefore frequently deleted or mutated in cancer. For tumors with wild-type p53, its function can be overcome by overactive cellular antagonists, such as the ubiquitin ligase murine double minute clone 2 (MDM2). Restoring p53 activity by inhibiting MDM2 in such cancers can eradicate tumors. Consequently, the MDM2-p53 interaction has been extensively targeted for inhibition by small molecules. In recent years, MDM2-like protein (MDMX), another key downregulator of p53, has gained increasing importance as an additional target for drug development, in order to provide a complementary approach to MDM2 inhibition. In this review, we describe how detailed structural knowledge of the MDM2-p53 interface and, more recently, of the MDMX-p53 interaction have helped advance the development of inhibitors against the two targets. We present a summary of the functional biochemistry of MDM2, MDMX and p53 as well as their interactions and examine recent progress in the development of inhibitors of MDM2 and MDMX.

Novel targeted therapeutics: inhibitors of MDM2, ALK and PARP

We reviewed preclinical data and clinical development of MDM2 (murine double minute 2), ALK (anaplastic lymphoma kinase) and PARP (poly [ADP-ribose] polymerase) inhibitors. MDM2 binds to p53, and promotes degradation of p53 through ubiquitin-proteasome degradation. JNJ-26854165 and RO5045337 are 2 small-molecule inhibitors of MDM2 in clinical development. ALK is a transmembrane protein and a member of the insulin receptor tyrosine kinases. EML4-ALK fusion gene is identified in approximately 3-13% of non-small cell lung cancer (NSCLC). Early-phase clinical studies with Crizotinib, an ALK inhibitor, in NSCLC harboring EML4-ALK have demonstrated promising activity with high response rate and prolonged progression-free survival. PARPs are a family of nuclear enzymes that regulates the repair of DNA single-strand breaks through the base excision repair pathway. Randomized phase II study has shown adding PARP-1 inhibitor BSI-201 to cytotoxic chemotherapy improves clinical outcome in patients with triple-negative breast cancer. Olaparib, another oral small-molecule PARP inhibitor, demonstrated encouraging single-agent activity in patients with advanced breast or ovarian cancer. There are 5 other PARP inhibitors currently under active clinical investigation.

Understanding small-molecule binding to MDM2: insights into structural effects of isoindolinone inhibitors from NMR spectroscopy

The interaction between murine double minute (MDM2) and p53 is a major target in anticancer drug design. Several potent compound series, including the nutlins and spirooxindoles, have previously been established as high-affinity antagonists of MDM2. In this paper, we describe the interaction of isoindolinone inhibitors with MDM2, as characterized by nuclear magnetic resonance spectroscopy. Isoindolinone inhibitors bind specifically to the MDM2 p53 binding site and exploit all sub-pockets used by p53, nutlins and spirooxindoles. Furthermore, isoindolinones bind with low micromolar to high nanomolar affinities, with the best compound approaching the potency of nutlin-3.

NMR-based screening of membrane protein ligands

Membrane proteins pose problems for the application of NMR-based ligand-screening methods because of the need to maintain the proteins in a membrane mimetic environment such as detergent micelles: they add to the molecular weight of the protein, increase the viscosity of the solution, interact with ligands non-specifically, overlap with protein signals, modulate protein dynamics and conformational exchange and compromise sensitivity by adding highly intense background signals. In this article, we discuss the special considerations arising from these problems when conducting NMR-based ligand-binding studies with membrane proteins. While the use of (13)C and (15)N isotopes is becoming increasingly feasible, (19)F and (1)H NMR-based approaches are currently the most widely explored. By using suitable NMR parameter selection schemes independent of or exploiting the presence of detergent, (1)H-based approaches require least effort in sample preparation because of the high sensitivity and natural abundance of (1)H in both, ligand and protein. On the other hand, the (19)F nucleus provides an ideal NMR probe because of its similarly high sensitivity to that of (1)H and the lack of natural (19)F background in biologic systems. Despite its potential, the use of NMR spectroscopy is highly underdeveloped in the area of drug discovery for membrane proteins.

The p53-MDM2/MDMX axis - A chemotype perspective

The protein-protein interaction (PPI) of the tumor suppressor p53 and its negative regulator MDM2 consists of the most intense studied PPI with a group of small molecular weight antagonists described and many more disclosed in patent literature. Due to the Å-level structural insight into p53 interaction with MDM2 there is a reasonable understanding of the requirements of the molecules to bind. In contrast and despite the very close homology and 3-D similarity no potent MDMX antagonist has been disclosed up to date. The current review summarizes the different disclosed chemotypes for MDM2 including a discussion of the cocrystal structures. Structures and approaches to reconstitute functional p53 from mutated p53 are presented. Finally new screening methods and recent biotech deals based on p53 are discussed.

On the industrial applications of MCRs: molecular diversity in drug discovery and generic drug synthesis

During the last decades, multicomponent chemistry has gained much attention in pharmaceutical research, especially in the context of lead finding and optimization. Here, in particular, the main advantages of multicomponent reactions (MCRs) like ease of automation and high diversity generation were utilized. In consequence of these beneficial properties, a plethora of new MCRs combined with appropriate classical reaction sequences have been published, the accessible chemical space was extended steadily. In the meantime, the desired high diversity became a challenge itself, because by now the systematic use of this huge and unmanageable space for drug discovery was limited by the lack of suitable computational tools. Therefore, this article provides an insight for the rational use of this enormous chemical space in drug discovery and generic drug synthesis. In this context, a short overview of the applied chemo informatics, necessary for the virtual screening of the biggest available chemical space, is given. Furthermore, some examples for recently developed multicomponent sequences are presented.

Methyl trans-(±)-1-oxo-2-phenethyl-3-(thio-phen-2-yl)-1,2,3,4-tetra-hydro-isoquinoline-4-carboxyl-ate

In the title compound, C(23)H(21)NO(3)S, the piperidine ring of the tetra-hydro-isoquinolinone unit adopts a screw-boat conformation. The thio-phene ring is disordered in a 0.700 (3):0.300 (3) ratio by an approximate 180° rotation of the ring around the C-C bond linking the ring to the tetra-hydro-isoquinolinone unit. The benzene ring of the tetra-hydro-isoquinolinone unit makes dihedral angles of 83.1 (2) and 62.38 (11)° with the major occupancy thio-phene ring and the phenyl ring, respectively. The dihedral angle between the phenyl ring and the thio-phene ring is 71.0 (2)°. In the crystal structure, mol-ecules are linked together by inter-molecular C-H⋯O and C-H⋯π inter-actions.

Targeting Mdm2 and Mdmx in cancer therapy: better living through medicinal chemistry?

Genomic and proteomic profiling of human tumor samples and tumor-derived cell lines are essential for the realization of personalized therapy in oncology. Identification of the changes required for tumor initiation or maintenance will likely provide new targets for small-molecule and biological therapeutics. For example, inactivation of the p53 tumor suppressor pathway occurs in most human cancers. Although this can be due to frank p53 gene mutation, almost half of all cancers retain the wild-type p53 allele, indicating that the pathway is disabled by other means. Alternate mechanisms include deletion or epigenetic inactivation of the p53-positive regulator arf, methylation of the p53 promoter, or elevated expression of the p53 regulators Mdm2 and Mdmx. This review discusses current models of p53 regulation by Mdm2 and Mdmx and presents the rationale for design of future Mdmx-specific therapeutics based on our knowledge of its structure and biological functions.

Therapeutic considerations for Mdm2: not just a one trick pony

BACKGROUND: The mdm2 proto-oncogene is elevated in numerous late stage cancers. The Mdm2 protein manifests its oncogenic properties in part through inactivation of the tumor suppressor protein p53. Recent efforts in anti-cancer drug design have focused on the identification of small molecules that disrupt the Mdm2-p53 interaction, in hopes of re-engaging the p53 pathway. OBJECTIVE: In addition to binding p53, Mdm2 complexes with numerous proteins involved in DNA repair, translation, metabolic activities, tumor growth and apoptosis. Additional biochemical analysis is required to understand how Mdm2 integrates into all of these cellular processes. Post-translational modifications to Mdm2 can alter its ability to associate with numerous proteins. Changes in protein structure may also affect the ability of small molecule inhibitors to effectively antagonize Mdm2. CONCLUSION: The complexity of Mdm2 modification has been largely neglected during the development of previous Mdm2 inhibitors. Future high-throughput or in silico screening efforts will need to recognize the importance of post-translational modifications to Mdm2. Furthermore, the identification of molecules that target other domains in Mdm2 may provide a tool to prevent other pivotal p53-independent functions of Mdm2. These aims provide a useful roadmap for the discovery of new Mdm2 binding compounds with therapeutic potency that may exceed its predecessors.

trans-rac-[1-Oxo-2-phenethyl-3-(2-thien-yl)-1,2,3,4-tetra-hydro-isoquinolin-4-yl]methyl 4-methyl-benzene-sulfonate

The title compound, C₂₉H₂₇NO₄S₂, was synthesized by reaction of trans-rac-4-(hydroxy­meth­yl)-2-phenethyl-3-(thio­phen-2-yl)-3,4-dihydro­isoquinolin-1(2H)-one and 4-methyl­benzene-1-sulfonyl chloride in the presence of Et₃N in CH₂Cl₂. The relative orientations of the benzene ring (A) of the 3,4-dihydro­isoquinolinone ring system, the thio­phene ring (B), the benzene ring (C) of the methyl­benzene group and the phenyl ring (D) result in the following dihedral angles: A/B = 80.91 (16), A/C = 22.79 (18), A/D = 9.9 (2), B/C = 80.73 (19), B/D = 88.9 (2) and C/D = 29.9 (2)°. The crystal structure is stabilized by weak inter­molecular C—H⋯O hydrogen bonds and C—H⋯π inter­actions.