Synthesis, biological evaluation and X-ray analysis of bicalutamide sulfoxide analogues for the potential treatment of prostate cancer.

The androgen receptor (AR) is a pivotal target for the treatment of prostate cancer (PC) even when the disease progresses toward androgen-independent or castration-resistant forms. In this study, a series of sulfoxide derivatives were prepared and their antiproliferative activity evaluated in vitro against four different human prostate cancer cell lines (22Rv1, DU-145, LNCaP and VCap). Bicalutamide and enzalutamide were used as positive controls. Compound 28 displayed significant enhancement in anticancer activity across the four PC cell lines with IC50 = 9.09 - 31.11 µM compared to the positive controls: bicalutamide (IC50 = 45.20 -51.61 µM) and enzalutamide (IC50 = 11.47 - 53.04 µM). Sulfoxide derivatives of bicalutamide were prepared efficiently from the corresponding sulfides using only one equivalent of mCPBA, limiting the reaction time to 15-30 min and maintaining the temperature at 0 °C. Interestingly, three pairs of sulfoxide diastereomers were separated and NMR comparison of their diastereotopic methylene (CH2) group is presented. X-ray diffraction crystal structure analysis provided relative configuration assignment at the chiral sulfur and carbon centres. Molecular modelling study of the four diastereoisomers of compound 28 is described.

Multivariate analysis in the development of bioequivalent tablets containing bicalutamide.

The pharmaceutical industry has to tackle the explosion of high amounts of poorly soluble APIs. This phenomenon leads to numerous sophisticated solutions. These include the use of multifactorial data analysis identifying correlations between the components and dosage form properties, laboratory and production process parameters with respect to the API liberation Example of such API is bicalutamide. Improved liberation is achieved by particle size reduction. Laboratory batches, with different PSD of API, were filled into gelatinous capsules and consequently granulated for tablet compression. Comparative dissolution profiles with Casodex 150 mg (Astra Zeneca) were performed. The component analysis was used for the statistical evaluation of f1 and f2 factors and D(v,0.9) and D[4,3] parameters of PSD to identify optimal PSD values. Suitable PSD limits for API were statistically confirmed in laboratory and in commercial scale with respect to optimized tablet properties. The tablets were bioequivalent with originator (n = 20; 90% CI for ln AUC0-120: 99.8-111.9%; 90% CI for ln cmax: 101.1-112.9%). In conclusion, the micronisation of the API is still an efficient and inexpensive method improving the bioavailability, although there are more complicated and expensive methods available. Statistical multifactorial methods improved the safety and reproducibility of production.

Synthesis and Biological Evaluation of Bicalutamide Analogues for the Potential Treatment of Prostate Cancer.

The androgen receptor (AR) is a pivotal target for the treatment of prostate cancer (PC) even when the disease progresses toward androgen-independent or castration-resistant forms. In this study, a series of 15 bicalutamide analogues (sulfide, deshydroxy, sulfone, and O-acetylated) were prepared and their antiproliferative activity evaluated against four different human prostate cancer cell lines (22Rv1, DU-145, LNCaP, and VCap). Bicalutamide and enzalutamide were used as positive controls. Seven of these compounds displayed remarkable enhancement in anticancer activity across the four PC cell lines. The deshydroxy analogue (16) was the most active compound with IC50 = 6.59-10.86 µM. Molecular modeling offers a plausible explanation of the higher activity of the sulfide analogues compared to their sulfone counterparts.

Ni/Co-Catalyzed Homo-Coupling of Alkyl Tosylates.

A direct reductive homo-coupling of alkyl tosylates has been developed by employing a combination of nickel and nucleophilic cobalt catalysts. A single-electron-transfer-type oxidative addition is a pivotal process in the well-established nickel-catalyzed coupling of alkyl halides. However, the method cannot be applied to the homo-coupling of ubiquitous alkyl tosylates due to the high-lying σ*(C-O) orbital of the tosylates. This paper describes a Ni/Co-catalyzed protocol for the activation of alkyl tosylates on the construction of alkyl dimers under mild conditions.

11a-N-tosyl-5-carbapterocarpans: Synthesis, antineoplastic evaluation and in silico prediction of ADMETox properties.

11a-N-tosyl-5-carbapterocarpans (5a-c and 6a-c), 9-N-tosyl-4,4a,9,9a-tetrahydro-3H-carbazole (7), 11a-N-tosyl-5-carbapterocarpen (8) analogues of LQB-223 (4a), were synthesized through palladium catalyzed azaarylation of substituted dihydronaphtalenes (14a-c) and cyclohexadiene (15), respectively, with N-tosyl-o-iodoaniline (11). In order to understand the role of the N-tosyl moiety for the pharmacological activity, the azacarbapterocarpen (9) was also synthesized by Fischer indol reaction. The structural requirements at the A and D-rings for the antineoplastic activity toward human leukemias and breast cancer cells were evaluated as well. Substitutions on the A-ring of 4a and analogues alter the effect on different breast cancer subtypes. On the other hand, A-ring is not essential for antileukemic activity since compound 7, which does not contain the A-ring, showed efficacy with high selectivity indices for drug-resistant leukemias. On the other hand, substitutions on the D-ring of 4a for fluorine or iodine did not improve the antileukemic activity. In silico studies concerning Lipinskís rule of five, ADMET properties and drug scores of those compounds were performed, indicating good physicochemical properties for all compounds, in special for compound 7.

Synthesis of 3-Methylidene-1-tosyl-2,3-dihydroquinolin-4(1H)-ones as Potent Cytotoxic Agents.

An efficient synthetic strategy to 3-methylidene-2,3-dihydroquinolin-4(1H)-ones variously substituted in position 2 has been developed. The title compounds were synthesized in the reaction sequence involving reaction of diethyl methylphosphonate with methyl 2-(tosylamino)benzoate, condensation of thus formed diethyl 2-oxo-2-(2-N-tosylphenyl)ethylphosphonate with various aldehydes followed by successful application of the obtained 3-(diethoxyphosphoryl)-1,2-dihydroquinolin-4-ols as Horner-Wadsworth-Emmons reagents for the olefination of formaldehyde. Also, enantioselective approach to the target compounds has been evaluated using 3-dimenthoxyphosphoryl group as a chiral auxiliary. Single X-ray crystal analysis of (2S)-3-(dimenthoxyphosphoryl)-2-phenyl-1-tosyldihydroquinolin-4-ol revealed the presence of strong resonance-assisted hydrogen bond (RAHB). The obtained 3-methylidene-2,3-dihydroquinolin-4(1H)-ones were then tested for their cytotoxic activity against two leukemia cell lines NALM-6 and HL-60 and a breast cancer MCF-7 cell line. All compounds showed very high cytotoxic activity with the IC50 values mostly below 1 µm in all three cancer cell lines. The selected analogs were also tested on human umbilical vein endothelial cells (HUVEC) and on human mammary gland/breast cells (MCF-10A) to evaluate their influence on normal cells. Since one of the most serious problems in cancer chemotherapy is the development of drug resistance, the mRNA levels and activity of ABCB1 transporter considered to be the most important factor engaged in drug resistance, were evaluated in MCF-7 cells treated with two selected analogs. Both compounds were strong ABCB1 transporter inhibitors that could prevent efflux of anticancer drugs from cancer cells.

Acyclic 1,4-Stereocontrol via the Allylic Diazene Rearrangement: Development, Applications, and the Essential Role of Kinetic E Stereoselectivity in Tosylhydrazone Formation.

We report full details of a method for 1,3-reductive transposition of α-alkoxy-α,ß-unsaturated hydrazones to provide E-alkenes with high 1,4-stereocontrol between the two respective allylic stereocenters. The process couples a chelation-controlled reduction of the hydrazone with an in situ allylic strain controlled retro-ene reaction of an allyl diazene, i.e., an allylic diazene rearrangement. Such stereotriads are frequently observed motifs in natural products. We observed a fortuitous kinetic preference for the E-hydrazone geometry during the hydrazonation reaction, as only the E-isomers could undergo chelation-controlled reduction.

One-Pot Synthesis of ß-Hydroxysulfones and Its Application in the Preparation of Anticancer Drug Bicalutamide.

An efficient one-pot multistep strategy has been developed, comprising auto-oxidative difunctionalization of alkenes, oxidation of sulfides, and a further reduction of peroxides for the synthesis of complex ß-hydroxysulfone derivatives from phenthiols and alkenes. This method has several advantageous characteristics, including readily available substrates, low-cost and environmental benign reagents, nontoxic and renewable solvents, and mild reaction conditions. The application of this transformation to the multigram-scale preparation of the anticancer drug bicalutamide is accomplished.

Titania-catalyzed radiofluorination of tosylated precursors in highly aqueous medium.

Nucleophilic radiofluorination is an efficient synthetic route to many positron-emission tomography (PET) probes, but removal of water to activate the cyclotron-produced [(18)F]fluoride has to be performed prior to reaction, which significantly increases overall radiolabeling time and causes radioactivity loss. In this report, we demonstrate the possibility of (18)F-radiofluorination in highly aqueous medium. The method utilizes titania nanoparticles, 1:1 (v/v) acetonitrile-thexyl alcohol solvent mixture, and tetra-n-butylammonium bicarbonate as a phase-transfer agent. Efficient radiolabeling is directly performed with aqueous [(18)F]fluoride without the need for a drying/azeotroping step to significantly reduce radiosynthesis time. High radiochemical purity of the target compound is also achieved. The substrate scope of the synthetic strategy is demonstrated with a range of aromatic, aliphatic, and cycloaliphatic tosylated precursors.

Cs2CO3-promoted carboxylation of N-tosylhydrazones with carbon dioxide toward α-arylacrylic acids.

A Cs2CO3-promoted carboxylation of N-tosylhydrazones and CO2 has been developed. The reaction proceeded efficiently at 80 °C under atmospheric CO2, gave the corresponding α-arylacrylic acids in moderate to good yields. This method was featured with (1) the employment of Cs2CO3 rather than (n)BuLi as the base; (2) a reaction temperature of 80 °C rather than -78 °C.

Copper(I)-catalyzed alkylation of polyfluoroarenes through Direct C-H bond functionalization.

The copper(I)-catalyzed alkylation of electron-deficient polyfluoroarenes with N-tosylhydrazones and diazo compounds has been developed. This reaction uses readily available starting materials and is operationally simple, thus representing a practical method for the construction of C(sp(2) )-C(sp(3) ) bonds with polyfluoroarenes through direct C-H bond functionalization. Mechanistically, copper(I) carbene formation and subsequent migratory insertion are proposed as the key steps in the reaction pathway.

N-benzoyl- and N-sulfonyl-1,5-benzodiazepines: comparison of their atropisomeric and conformational properties.

The atropisomeric and conformational properties of 1,5-benzodiazepines with an N-sulfonyl (p-tosyl/mesyl) group (IIa/b) were investigated by comparison with those of the N-benzoyl congeners (I). Similar to I, when the Ar-N(SO2) axis was frozen by a C9-substitution in the molecules, IIa/b were separated into the (aR)- and (aS)-atropisomers. The conformation of IIa/b revealed that the substituent (p-tolyl/methyl group) in the sulfonyl moiety occupies the position over the diazepine ring (folded form) in both the solid and solution states [e.g., (+)-(aR)-N-p-tosyl-1,5-benzodiazepin-2-one (IIa-2)], whereas that of I is anti to the diazepine ring [e.g., (-)-(aR)-N-benzoyl-1,5-benzodiazepin-2-one (I-2)], which was further supported by a computational study. The stereochemical stability also differed between the two congeners (e.g., ΔG(‡): 104 kJ/mol for I-2 and 132 kJ/mol for IIa-2).

Tandem one-pot palladium-catalyzed coupling of hydrazones, haloindoles, and amines: synthesis of amino-N-vinylindoles and their effect on human colon carcinoma cells.

The synthesis of amino-substituted N-vinylazoles was achieved by a new palladium-assisted tandem catalytic reaction involving N-tosylhydrazones, halo-substituted azoles, and amines. Accordingly, two Csp(2)-N bonds were formed through two mechanistically distinct reactions using a single Pd(II)/Pd(0) catalyst system in a one-pot fashion. This work paves the way for the design of biological relevant compounds in an amino-substituted N-vinylindole series. Among several polyoxygenated derivatives evaluated, compounds 5e and 5u were found to exhibit good antiproliferative activity.

Efficient, scalable and economical preparation of tris(deuterium)- and 13C-labelled N-methyl-N-nitroso-p-toluenesulfonamide (Diazald®) and their conversion to labelled diazomethane.

A method for the preparation of multi-gramme quantities of N-methyl-d3-N-nitroso-p-toluenesulfonamide (Diazald-d3) and N-methyl-(13)C-N-nitroso-p-toluenesulfonamide (Diazald-(13)C) and their conversion to diazomethane-d2 and diazomethane-(13) C, respectively, is presented. This approach uses robust and reliable chemistry, and critically, employs readily commercially available and inexpensive methanol as the label source. Several reactions of labelled diazomethane are also reported, including alkene cyclopropanation, phenol methylation and α-diazoketone formation, as well as deuterium scrambling in the preparation of diazomethane-d2 and subsequent methyl esterification of benzoic acid.

Copper-catalyzed one-pot trifluoromethylation/aryl migration/desulfonylation and C(sp2)-N bond formation of conjugated tosyl amides.

A novel copper-catalyzed one-pot trifluoromethylation/aryl migration/desulfonylation and C(sp(2))-N bond formation with conjugated tosyl amides as starting materials is presented here. The reaction affords α-aryl-ß-trifluoromethyl amides bearing a quaternary stereocenter or trifluoromethylated oxindoles in a regioselective manner.

A new series of N2-substituted-5-(p-toluenesulfonylamino)phthalimide analogues as α-glucosidase inhibitors.

Several members of a new family of non-sugar-type α-glycosidase inhibitors, bearing a 5-(p-toluenesulfonylamino)phthalimide moiety and various substituent at the N2 position, were synthesized and their activities were investigated. The newly synthesized compounds displayed different inhibition profile towards yeast α-glycosidase and rat intestinal α-glycosidase. Almost all the compounds had strong inhibitory activities against yeast α-glycosidase. Regarding rat intestinal α-glycosidase, only analogs with N2-aromatic substituents displayed varying degrees of inhibitory activities on rat intestinal maltase and lactase and nearly all compounds showed no inhibition against rat intestinal α-amylase. Structure-activity relationship studies indicated that 5-(p-toluenesulfonylamino)phthalimide moiety is a favorable scaffold to exert the α-glucosidase inhibitory activity and substituents at the N2 position have considerable influence on the efficacy of the inhibition activities.

Native FKBP12 engineering by ligand-directed tosyl chemistry: labeling properties and application to photo-cross-linking of protein complexes in vitro and in living cells.

The ability to modify target "native" (endogenous) proteins selectively in living cells with synthetic molecules should provide powerful tools for chemical biology. To this end, we recently developed a novel protein labeling technique termed ligand-directed tosyl (LDT) chemistry. This method uses labeling reagents in which a protein ligand and a synthetic probe are connected by a tosylate ester group. We previously demonstrated its applicability to the selective chemical labeling of several native proteins in living cells and mice. However, many fundamental features of this chemistry remain to be studied. In this work, we investigated the relationship between the LDT reagent structure and labeling properties by using native FK506-binding protein 12 (FKBP12) as a target protein. In vitro experiments revealed that the length and rigidity of the spacer structure linking the protein ligand and the tosylate group have significant effects on the overall labeling yield and labeling site. In addition to histidine, which we reported previously, tyrosine and glutamate residues were identified as amino acids that are modified by LDT-mediated labeling. Through the screening of various spacer structures, piperazine was found to be optimal for FKBP12 labeling in terms of labeling efficiency and site specificity. Using a piperazine-based LDT reagent containing a photoreactive probe, we successfully demonstrated the labeling and UV-induced covalent cross-linking of FKBP12 and its interacting proteins in vitro and in living cells. This study not only furthers our understanding of the basic reaction properties of LDT chemistry but also extends the applicability of this method to the investigation of biological processes in mammalian cells.

Synthesis of 2-azaspiro[4.6]undec-7-enes from N-tosyl-N-(3-arylpropargyl)-tethered 3-methylcyclohex-2-en-1-ols.

The FeCl(3)-promoted synthesis of 2-azaspiro[4.6]undec-7-ene rings proceeds via ring expansion/cyclization/chlorination of N-tosyl-N-(3-arylpropargyl)-tethered 6-methylbicyclo[4.1.0]heptan-2-ols. This azaspirocyclic ring skeleton can also be obtained in one pot from the tert-butyldimethylsilyl-protected N-tosyl-N-(3-arylpropargyl)-tethered 3-methylcyclohex-2-en-1-ols and diethylzinc/diiodomethane.

One-step cyclization: synthesis of N-heteroalkyl-N'-tosylpiperazines.

Piperazine derivatives are important intermediates in organic synthesis and useful building blocks in pharmaceutical and fine chemical industries. Currently available synthetic routes for these heterocyclic compounds have limited scope owing to the harsh reaction conditions, low yields, and multistep process. Herein, we reported a practical method for synthesis of alkyl-, alcohol-, amine-, and ester-extended tosylpiperazines under mild conditions with moderate to high yields. This protocol exhibits potential applicability in the synthesis of pharmaceuticals and natural products because of the operational simplicity and the conveniently available reactants. On the basis of the experimental and theoretical results, a plausible mechanism of aliphatic nucleophilic substitution (S(N)) in the cyclization has been postulated and evidence for the formation of a six-membered ring has also been confirmed by means of density functional theory (DFT) calculations.

Regiospecific syntheses of functionalized diaryliodonium tosylates via [hydroxy(tosyloxy)iodo]arenes generated in situ from (diacetoxyiodo)arenes.

Ready access to (18)F-labeled aryl synthons is required for preparing novel radiotracers for molecular imaging with positron emission tomography. Diaryliodonium salts react with cyclotron-produced no-carrier-added [(18)F]fluoride ion to produce [(18)F]aryl fluorides. We aimed to prepare functionalized diaryliodonium salts to serve as potential precursors for producing useful (18)F-labeled aryl synthons, such as (18)F-labeled halomethylbenzenes, benzaldehydes, and benzoic acid esters. Such salts were designed to have one functionalized aryl ring, one relatively electron-rich ring, such as 4-methoxyphenyl or 2-thienyl, and a nonfluorine containing weakly nucleophilic anion. Generation of a [hydroxy(tosyloxy)iodo]arene from a functionalized (diacetoxyiodo)arene in situ followed by treatment with an electron-rich arene, such as anisole or thiophene, or with a functionalized arylstannane gave expedient regiospecific access to a wide range of functionally diverse diaryliodonium tosylates in moderate to high yields (44-98%). The described methodology broadens the scope for producing new functionalized diaryliodonium salts for diverse applications.