Design, Synthesis, and in Vivo SAR of a Novel Series of Pyrazolines as Potent Selective Androgen Receptor Modulators

Nickel-Catalyzed Multicomponent Assembly of Alkynes toward α-CF3-Alkenes

We disclose an efficient nickel catalytic system for expediting the coupling of alkynes with fluoroalkyl hydrazones and boronic acids, thus facilitating the synthesis of stereospecific α-fluoroalkyl-alkene derivatives. 3H-Pyrazoles might be involved as key intermediates through a nitrogen-releasing process, enabling subsequent coupling with boronic acids to afford 1,2-difunctional alkenes in a highly efficient and step-economical fashion. This tandem platform demonstrates broad functional group tolerance, including complex natural products and drug-like molecules.

Tandem Addition/Cyclization/Halogenation Reaction of Difluoromethylated N-Acylhydrazones with Allyltrimethylsilanes

As novel difluoromethyl building blocks, difluoromethylated N-acylhydrazones react with allyltrimethylsilanes and the halogen source via a tandem addition/cyclization/halogenation strategy, which produces various difluoromethylpyrazoline compounds in good yields. The method features mild reaction conditions, broad substrate scopes, and a transition metal-free process with easy operation. It also proves that difluoromethylated N-acylhydrazones are useful difluoromethyl building blocks for the construction of difluoromethylated nitrogen heterocycles.

Trifluoromethylated hydrazones and acylhydrazones as potent nitrogen-containing fluorinated building blocks

Nitrogen-containing organofluorine derivatives, which are prepared using fluorinated building blocks, are among the most important active fragments in various pharmaceutical and agrochemical products. This review focuses on the reactivity, synthesis, and applications of fluoromethylated hydrazones and acylhydrazones. It summarizes recent methodologies that have been used for the synthesis of various nitrogen-containing organofluorine compounds.

Synthesis of 2-Pyrazolines with a CF3- and Alkyne-Substituted Quaternary Carbon Center via [3 + 2] Cycloaddition of β-CF3-1,3-enynes and Diazoacetates

Given the importance of both the CF₃ group and the alkyne moiety in synthetic/medicinal chemistry, we report here the first example of efficient synthesis of 2-pyrazolines with a CF₃- and alkyne-substituted quaternary carbon center. This methodology has the advantages of high functional group compatibility, the avoidance of base and open-flask conditions, easily available and easy to handle reagent, and broad substrate scope. Notably, this protocol allows for the late-stage functionalization of biologically active molecules and the gram-scale synthesis.

Therapeutic Strategies to Target the Androgen Receptor

The androgen receptor (AR) plays a key role in the maintenance of muscle and bone and the support of male sexual-related functions, as well as in the progression of prostate cancer. Accordingly, AR-targeted therapies have been developed for the treatment of related human diseases and conditions. AR agonists are an important class of drugs in the treatment of bone loss and muscle atrophy. AR antagonists have also been developed for the treatment of prostate cancer, including metastatic castration-resistant prostate cancer (mCRPC). Additionally, selective AR degraders (SARDs) have been reported. More recently, heterobifunctional degrader molecules of AR have been developed, and four such compounds are now in clinical development for the treatment of human prostate cancer. This review attempts to summarize the different types of compounds designed to target AR and the current frontiers of research on this important therapeutic target.

Efficiently enantioselective synthesis of pyrazolines and isoxazolines enabled by iridium-catalyzed intramolecular allylic substitution reactions

An efficient Ir-catalyzed enantioselective intramolecular allylic substitution reaction of 2-tosylhydrazono or hydroxyimino carbonates for the synthesis of pyrazolines and isoxazolines has been achieved. The products were obtained in high yield...

Copper(i)-catalyzed asymmetric [3 + 2] cycloaddition of N-ester acylhydrazones and β-trifluoromethyl-α,β-unsaturated ketones

The first copper(i)-catalyzed asymmetric [3 + 2] cycloaddition of N-ester acylhydrazones and ketones has been developed, affording an array of chiral pyrazolidines containing a trifluoromethyl moiety bearing three vicinal stereocenters.

Photocatalytic three-component radical cascade: a general route to heterocyclic-substituted alkyl sulfones

A photoredox-catalyzed three-component radical cascade reaction of β,γ-unsaturated oximes/hydrazones, the sulfur dioxide surrogate of DABCO·(SO2)2 and alkenes under mild conditions is developed.

Metal-free [3+2] cycloaddition of glycosyl olefinic ester with in situ generated CF3CHN2: Access to CF3-substituted pyrazoline glycoconjugates

An efficient [3 + 2] cycloaddition of glycosyl olefinic ester with in situ generated CF₃CHN₂ for the syntheses of CF₃-substituted pyrazoline glycoconjugate has been developed. This mild, one-pot reaction condition avoiding the use of metallic catalyst and additive will be useful in the pharmaceutical industry. This reaction features are the broad substrate scope, good functional group tolerance with good to high yields.

Asymmetric Aza-Wacker-Type Cyclization of N-Ts Hydrazine-Tethered Tetrasubstituted Olefins: Synthesis of Pyrazolines Bearing One Quaternary or Two Vicinal Stereocenters

We have developed an asymmetric aza-Wacker-type cyclization of N-Ts hydrazine-tethered tetrasubstituted olefins, affording optically active pyrazolines bearing chiral tetrasubstituted carbon stereocenters. This reaction is tolerant to a broad range of substrates under mild reaction conditions, giving the desired chiral products with high enantioselectivities. Generation of two vicinal stereocenters on the C═C double bonds was also achieved with high selectivities, a process which has been rarely studied for Wacker-type reactions. A mechanistic study revealed that this aza-Wacker-type cyclization undergoes a syn-aminopalladation process. It was also found that for substrates bearing two linear alkyl substituents on the outer carbon atom of the olefin, both of which are larger than a methyl group, the alkyl substituent that is cis to the intranucleophilic group participates more readily in β-hydride elimination. When one of the two alkyl substituents on the outer carbon atom of the olefin is a methyl group, β-hydride elimination proceeds selectively at the methylene side, thus both diastereomers can be prepared via switching the configuration of the olefin. Furthermore, the product can be converted to a pharmaceutical compound in high yields over three steps.

Cascade Oxidation/Halogenoaminocyclization Reaction of Trifluoromethylated Homoallylic N-Acylhydrazines: Metal-free Synthesis of CF3-Substituted Pyrazolines

An efficient and practical cascade oxidation/halogenoaminocyclization of trifluoromethylated homoallylic N-acylhydrazines is developed. The protocol enables an efficient access to various biologically interesting CF₃-containing pyrazoline compounds from readily accessible trifluoromethylated homoallylic N-acylhydrazines in good to excellent yields under mild conditions without any other additives or catalysts. The produced pyrazoline compounds can be further manipulated to other more complicated derivatives through transformation of residual halogen atom.

Synthesis of novel series of 7,7′-(substituted methylene)bis-imidazo[1,2-b]pyrazoles via an acid catalyzed one-pot three-component reaction

An efficient and rapid synthesis of new series of N-alkyl-2-aryl-5H-imidazo[1,2-b]pyrazoles has been achieved in high yields through a three-component reaction of 3-amino-4-substituted pyrazoles, aromatic aldehydes and isocyanides mediated by acid catalysts.

Structural elucidation of major selective androgen receptor modulator (SARM) metabolites for doping control

Elucidated and validated structure of the major SARM doping drug metabolites.

2-pyrazoline derivatives in neuropharmacology: Synthesis, ADME prediction, molecular docking and in vivo biological evaluation

A novel series of 1,3,5-trisubstituted-2-pyrazoline derivatives (PFC-1 to PFC-16) were synthesized in a three step reaction using conventional and microwave assisted green chemistry approach. The synthesized derivatives were characterized and their chemical structures were established by various physicochemical methods such as IR, Mass, ¹H-NMR, ¹³C-NMR and elemental analysis. The synthesized compounds were tested for their neuropharmacological potential. The compounds exhibited significant antidepressant and anti-anxiety activities against various behavioral in vivo models. Compounds PFC-3 and PFC-12 were found to be the most active derivatives in the series. The 2-pyrazoline analogs, having 2-hydroxyphenyl and anthracen-9-yl substitution at 3^rd position while 4-benzyloxyphenyl and 4-methylphenyl substitution at 5^th position, were decisive in eliciting good antidepressant and anxiolytic properties, respectively. The docking experiments revealed that the synthesized derivatives were potential inhibitors of MAO-A protein, which plays a central role in managing depression and anxiety disorders. The most potent derivatives were found to be involved in some key interactions with Tyr407, Tyr444, Phe352 and Ala68 amino acid residues at the binding site of MAO-A protein. All the synthesized derivatives successfully passed the pharmacokinetic barriers of absorption, distribution, metabolism and elimination as predicted using in silico techniques without showing any substantial indication of acute and neurotoxicity. This was further confirmed in the laboratory by performing acute toxicity studies as per OECD guidelines.

Microwave-assisted one-pot synthesis and antimicrobial evaluation of 2-(1-phenyl-3-(2-thienyl)-1H-pyrazol-4-yl)chroman-4-one derivatives

New hybrid compounds containing flavanone and pyrazoline motifs were synthesized by microwave irradiation and conventional heating methods using one-pot synthetic strategy. The products were evaluated for their antimicrobial activity.

Formation and aromatization of strained bicyclic pyrazolidines via tandem reaction of alkyl 2-aroyl-1-chlorocyclopropanecarboxylates with acylhydrazones

The formation and aromatization of strained bicyclic pyrazolidines.

Synthesis and preliminary investigations into novel 1,2,3-triazole-derived androgen receptor antagonists inspired by bicalutamide

A versatile and high yielding synthesis of novel androgen receptor (AR) antagonists is presented. Using this methodology, six 1,4-substituted-1,2,3-triazole derived bicalutamide mimics were synthesised in five steps and in isolated overall yields from 41% to 85%. Evaluation of these compounds for their anti-proliferative properties against androgen dependent (LNCaP) and independent (PC-3) cells showed promising IC50 values of 34-45 μM and 29-151 μM, respectively. The data suggest that the latter compounds may be an excellent starting point for the development of prostate cancer therapeutics for both androgen dependent and independent forms of this disease. Docking of these compounds (each enantiomer) in silico into the T877A mutated androgen receptor, as possessed by LNCaP cells, was also undertaken.

Mechanism and selectivity of N-triflylphosphoramide catalyzed (3(+) + 2) cycloaddition between hydrazones and alkenes

Brønsted acid catalyzed (3(+) + 2) cycloadditions between hydrazones and alkenes provide a general approach to pyrazolidines. The acidity of the Brønsted acid is crucial for the catalytic efficiency: the less acidic phosphoric acids are ineffective, while highly acidic chiral N-triflylphosphoramides are very efficient and can promote highly enantioselective cycloadditions. The mechanism and origins of catalytic efficiencies and selectivities of these reactions have been explored with density functional theory (M06-2X) calculations. Protonation of hydrazones by N-triflylphosphoramide produces hydrazonium-phosphoramide anion complexes. These ion-pair complexes are very reactive in (3(+) + 2) cycloadditions with alkenes, producing pyrazolidine products. Alternative 1,3-dipolar (3 + 2) cycloadditions with the analogous azomethine imines are much less favorable due to the endergonic isomerization of hydrazone to azomethine imine. With N-triflylphosphoramide catalyst, only a small distortion of the ion-pair complex is required to achieve its geometry in the (3(+) + 2) cycloaddition transition state. In contrast, the weak phosphoric acid does not protonate the hydrazone, and only a hydrogen-bonded complex is formed. Larger distortion energy is required for the hydrogen-bonded complex to achieve the "ion-pair" geometry in the cycloaddition transition state, and a significant barrier is found. On the basis of this mechanism, we have explained the origins of enantioselectivities when a chiral N-triflylphosphoramide catalyst is employed. We also report the experimental studies that extend the substrate scope of alkenes to ethyl vinyl ethers and thioethers.

Preliminary investigations into triazole derived androgen receptor antagonists

A range of 1,4-substituted-1,2,3-N-phenyltriazoles were synthesized and evaluated as non-steroidal androgen receptor (AR) antagonists. The motivation for this study was to replace the N-phenyl amide portion of small molecule antiandrogens with a 1,2,3-triazole and determine effects, if any, on biological activity. The synthetic methodology presented herein is robust, high yielding and extremely rapid. Using this methodology a series of 17 N-aryl triazoles were synthesized from commercially available starting materials in less than 3h. After preliminary biological screening at 20 and 40 μM, the most promising three compounds were found to display IC50 values of 40-50 μM against androgen dependent (LNCaP) cells and serve as a starting point for further structure-activity investigations. All compounds in this work were the focus of an in silico study to dock the compounds into the human androgen receptor ligand binding domain (hARLBD) and compare their predicted binding affinity with known antiandrogens. A comparison of receptor-ligand interactions for the wild type and T877A mutant AR revealed two novel polar interactions. One with Q738 of the wild type site and the second with the mutated A877 residue.

Pharmacological characterization of an imidazolopyrazole as novel selective androgen receptor modulator

Selective androgen receptor modulators (SARMs) are androgens with tissue-selective activity. SARMs that have anabolic activity on muscle while having minimal stimulatory activity on prostate are classified as SARM agonists. They can be used to prevent the loss of lean body mass that is associated with cancer, immunodeficiency, renal disease and aging. They may also have anabolic activity on bone; thus, unlike estrogens, they may reverse the loss of bone strength associated with aging or hypogonadism. Our in-house effort on SARM program discovers a nonsteroidal androgen receptor ligand with a unique imidazolopyrazole moiety in its structure. In vitro, this compound is a weak androgen receptor binder and a weak androgen agonist. Despite this, in orchidectomized mature rats it is an effective SARM agonist, with an ED(50) on levator ani muscle of 3.3mg/kg and an ED(50) on ventral prostate of >30mg/kg. It has its maximal effect on muscle at the dose of 10mg/kg. In addition, this compound has mixed agonistic and antagonistic activities on prostate, reducing the weight of that tissue in intact rats by 22% at 10mg/kg. The compound does not have significant effect on gonadotropin levels or testosterone levels in both orchidectomized and intact male rats. It does not have notable progestin, estrogen or glucocorticoid agonistic or antagonistic activity in rats. In a female sexual behavior model, it improves the sexual desire of ovariectomized female rats for sexually mature intact males over nonsexually ovariectomized females. Overall, the imidazolopyrazole is a potent prostate-sparing candidate for development as a SARM agonist with an appropriate pharmacological profile for clinical benefit in muscle-wasting conditions and female sexual function disorders.