Development of a Benzopyran-Containing Androgen Receptor Antagonist to Treat Antiandrogen-Resistant Prostate Cancer

Construction of efficient tung-oil-based thermal stabilizers bearing imide and epoxy groups for PVC

Tung-oil-derived imide epoxidized esters (GEABTMI) were successfully prepared and complexed with CaSt₂/ZnSt₂, which together displayed a good synergistic effect for stabilizing poly(vinyl chloride) (PVC).

Intramolecular Diaza-Diels-Alder Protocol: A New Diastereoselective and Modular One-Step Synthesis of Constrained Polycyclic Frameworks

Phenotype-based screening of diverse compound collections generated by privileged substructure-based diversity-oriented synthesis (pDOS) is considered one of the prominent approaches in the discovery of novel drug leads. However, one key challenge that remains is the development of efficient and modular synthetic routes toward the facile access of privileged small-molecule libraries with skeletal and stereochemical complexity and drug-like properties. In this regard, a novel and diverse one-pot procedure for the diastereoselective synthesis of privileged polycyclic benzopyrans and benzoxepines is described herein. These unexplored chemotypes were accessed by utilizing an acid-mediated diaza-Diels-Alder reaction of 2-allyloxy- and/or homoallyloxy benzaldehyde with 2-aminoazine building blocks. Profiling of representative analogues against blood-stage Plasmodium falciparum parasites identified three lead candidates with low micromolar antimalarial activity.

Inhibiting androgen receptor nuclear entry in castration-resistant prostate cancer

Clinical resistance to the second-generation antiandrogen enzalutamide in castration-resistant prostate cancer (CRPC), despite persistent androgen receptor (AR) activity in tumors, highlights an unmet medical need for next-generation antagonists. We have identified and characterized tetra-aryl cyclobutanes (CBs) as a new class of competitive AR antagonists that exhibit a unique mechanism of action. These CBs are structurally distinct from current antiandrogens (hydroxyflutamide, bicalutamide, and enzalutamide) and inhibit AR-mediated gene expression, cell proliferation, and tumor growth in several models of CRPC. Conformational profiling revealed that CBs stabilize an AR conformation resembling an unliganded receptor. Using a variety of techniques, it was determined that the AR-CB complex was not recruited to AR-regulated promoters and, like apo AR, remains sequestered in the cytoplasm, bound to heat shock proteins. Thus, we have identified third-generation AR antagonists whose unique mechanism of action suggests that they may have therapeutic potential in CRPC.

Diversity-oriented synthetic strategies applied to cancer chemical biology and drug discovery

How can diversity-oriented strategies for chemical synthesis provide chemical tools to help shape our understanding of complex cancer pathways and progress anti-cancer drug discovery efforts? This review (surveying the literature from 2003 to the present) considers the applications of diversity-oriented synthesis (DOS), biology-oriented synthesis (BIOS) and associated strategies to cancer biology and drug discovery, summarising the syntheses of novel and often highly complex scaffolds from pluripotent or synthetically versatile building blocks. We highlight the role of diversity-oriented synthetic strategies in producing new chemical tools to interrogate cancer biology pathways through the assembly of relevant libraries and their application to phenotypic and biochemical screens. The use of diversity-oriented strategies to explore structure-activity relationships in more advanced drug discovery projects is discussed. We show how considering appropriate and variable focus in library design has provided a spectrum of DOS approaches relevant at all stages in anti-cancer drug discovery.

High content screening of diverse compound libraries identifies potent modulators of tubulin dynamics

Tubulin modulating agents such as the taxanes are among the most effective antimitotic cancer drugs, although resistance and toxicity present significant problems in their clinical use. However, most tubulin modulators are derived from complex natural products, which can make modification of their structure to address these problems difficult. Here, we report the discovery of new antimitotic compounds with simple structures that can be rapidly synthesized, through the phenotypic screening of a diverse compound library for the induction of mitotic arrest. We first identified a compound, which induced mitotic arrest in human cells at submicromolar concentrations. Its simple structure enabled rapid exploration of activity, defining a biphenylacetamide moiety required for activity, A family of analogues was synthesized, yielding optimized compounds that caused mitotic arrest and cell death in the low nanomolar range, comparable to clinically used antimitotic agents. These compounds can be synthesized in 1-3 steps and good yields. We show that one such compound targets tubulin, partially inhibiting colchicine but not vinblastine binding, suggesting that it acts allosterically to the known colchicine-binding site. Thus, our results exemplify the use of phenotypic screening to identify novel antimitotic compounds from diverse chemical libraries and characterize a family of biphenylacetamides (biphenabulins) that show promise for further development.

Synthesis and library construction of privileged tetra-substituted Δ5-2-oxopiperazine as β-turn structure mimetics

In this study, we developed an efficient and practical procedure for the synthesis of tetra-substituted Δ5-2-oxopiperazine that mimics the bioactive β-turn structural motif of proteins. This synthetic route is robust and modular enough to accommodate four different substituents to obtain a high level of molecular diversity without any deterioration in stereochemical enrichment of the natural and unnatural amino acids. Through the in silico studies, including a distance calculation of side chains and a conformational overlapping of our model compound with a native β-turn structure, we successfully demonstrated the conformational similarity of tetra-substituted Δ5-2-oxopiperazine to the β-turn motif. For the library construction in a high-throughput manner, the fluorous tag technology was adopted with the use of a solution-phase parallel synthesis platform. A 140-membered pilot library of tetra-substituted Δ5-2-oxopiperazines was achieved with an average purity of 90% without further purification.

Privileged substructure-based diversity-oriented synthesis pathway for diverse pyrimidine-embedded polyheterocycles

A new diversity-oriented synthesis pathway for the fabrication of a pyrimidine-embedded polyheterocycles library was developed for potential interactions with diverse biopolymers. Five different pyrimidine-embedded core skeletons were synthesized from ortho-alkynylpyrimidine carbaldehydes by a silver- or iodine-mediated tandem cyclization strategy. The resulting polyheterocycles possess diverse fused ring sizes and positions with potential functionalities for further modification.

Generation of 6H-benzo[f]cyclopenta[d][1,2]thiazepine 5,5-dioxides via a palladium-catalyzed reaction of 2-(2-alkynyl)benzenesulfonamide

An efficient approach for the assembly of 6H-benzo[f]cyclopenta[d][1,2]thiazepine 5,5-dioxides via a palladium-catalyzed tandem reaction of 2-(2-alkynyl)benzenesulfonamide with 2-alkynylvinyl bromide is reported. This transformation proceeds smoothly through a double carbopalladation with high efficiency.

Construction of polyheterocyclic benzopyran library with diverse core skeletons through diversity-oriented synthesis pathway: part II

As a continuation of our previous report (J. Comb. Chem.2010, 12, 548-558), we accomplished the diversity-oriented synthesis of polyheterocyclic small-molecule library with privileged benzopyran substructure. To ensure the synthetic efficiency, we utilized the solid-phase parallel platform and the fluorous-tag-based solution-phase parallel platform to construct a 284-member polyheterocyclic library with six distinct core skeletons with an average purity of 87% on a scale of 5-10 mg. This library was designed to maximize the skeletal diversity with discrete core skeletons in three-dimensional space and the combinatorial diversity with four different benzopyranyl starting materials and various building blocks. Together with our reported benzopyranyl library, we completed the construction of polyheterocyclic benzopyran library with 11 unique scaffolds and their molecular diversity was visualized in chemical space using principle component analysis (PCA).

Regioselective construction and screening of 1,3-disubstituted tetrahydroindazolones in enantiomerically pure pairs

In this paper, we describe a regioselective synthetic pathway for enantiopure 1,3-disubstituted tetrahydroindazolone derivatives via the condensation of 2-acylcyclohexane-1,3-dione with various alkyl- and arylhydrazines using the steric effects of a Boc-protected pyrrolidine ring. This synthetic method has a broad scope for substrate generality for various hydrazines with excellent regioselectivity. To maximize the molecular diversity, further diversifications of 1,3-disubstituted tetrahydroindazolones were pursued by systematic N-modification of the secondary amine of the pyrrolidine ring using solution-phase parallel synthesis with polymer-supported reagents. A library containing a total of 272 drug-like tetrahydroindazolones, including 85 enantiomeric pairs, was constructed; the average purity, without further purification, was 95%.