Ionic liquid-promoted Wagner-Meerwein rearrangement of 16α,17α-epoxyandrostanes and 16α,17α-epoxyestranes

Ionic liquids 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim](+)[PF(6)](-)) and 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim](+)[BF(4)](-)) were found to promote an unusual Wagner-Meerwein rearrangement of steroidal 16α,17α-epoxides leading to unnatural 13-epi-18-nor-16-one derivatives as the main products. These compounds were isolated in good to excellent yields. 16α-Hydroxy-Δ(13)-18-norsteroids, the results of the usual rearrangement, were obtained as minor components of the reaction mixtures. The ionic liquid [bmim](+)[PF(6)](-) was shown to induce C-ring aromatization of 16α,17α-epoxyestranes due to the formation of HF, the hydrolysis product of [PF(6)](-). Increasing amounts of HF and [PO(2)F(2)](-) were detected by (19)F and (31)P NMR when the ionic liquid was reused. The structures of the steroidal products, 16-oxo-18-nor-13α-steroid derivatives, 16α-hydroxy-Δ(13)-18-norsteroids, and C-aromatic compounds were determined by two-dimensional NMR techniques and high-resolution mass spectrometry (HRMS). The ionic liquids were recirculated efficiently.     

Synthesis of nitrogen-containing derivatives of 17(20)-pregnenoic, 17β-hydroxypregnanoic,and 17α-hydroxypregnanoic acids as new potential antiandrogens

A general scheme for the synthesis of oxazoline and benzoxazole derivatives of [17(20)E]-21-norpregnene differing in the structure of the steroid moiety as well as amides of 17β-hydroxy-3-oxopregn-4-en-21-oic and 17α-hydroxy-3-oxopregn-4-en-21-oic acids was developed. The scheme involved synthesis of the steroid building blocks (appropriately protected derivatives of pregn-17(20)-en-21-oic, 17β-hydroxypregnan-21-oic, and 17α-hydroxypregnan-21-oic acids) and subsequent transformation of these building blocks into the target compounds. Following the developed scheme, synthesis of new nitrogen-containing steroid derivatives exhibiting antiandrogenic activity was enabled.     

13C NMR spectra of 17-substituted epimeric 17α and 17β-ethynylandrostenes and their hexacarbonyldicobalt complexes

¹³C NMR spectra of epimeric 17-R-substituted 17-ethynylandrostenes (R = H, OH, OAc, OMe, NCS) and 17-R-substituted 17-ethynylandrostenes (R = H, OH, OAc, OMe), and their hexacarbonyldicobalt complexes, as well as of ¹⁶-17-ethynylandrostenes and their hexacarbonyldicobalt complexes have been studied. Stereochemical dependence of C(12), C(14), C(18), C(20) and C(21) chemical shifts on the configuration of the substituents at C(17) has been demonstrated. The effect of Co-complexation on the spectral characteristics of Co-coordinated 17-ethynylandrostenes in both Stereochemical series has been investigated.Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 212–216, January, 1993.     

Wagner-Meerwein rearrangement of steviol 16α,17- and 15α,16-epoxides

16α,17- and 15α,16-Epoxy derivatives of diterpenoid steviol having ent-kaurane structure were found for the first time to undergo Wagner-Meerwein rearrangement in alkaline medium or by the action of boron trifluoride-diethyl ether complex to give products with ent-beyerane structure. The geometric parameters of steviol 16α,17- and 15α,16-epoxides were determined by X-ray analysis.     

Liquid chromatography-tandem mass spectrometry analysis of 17α-trenbolone, 17β-trenbolone and trendione in airborne particulate matter

Trenbolone acetate (TbA) is a potent synthetic anabolic steroid that was approved by the FDA as a growth promoter in beef cattle in 1987. Given the endocrine-modulating activity of TbA and its metabolites in all vertebrates, a sensitive and reliable analytical method is needed to detect TbA and related residues in environmental matrices. We have developed a method that incorporates solid phase extraction and liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the simultaneous determination of the three major TbA metabolites (trendione, 17β-trenbolone, 17α-trenbolone) in total suspended particulate matter (TSP) samples. Sample preparation involved pressurized liquid extraction followed by cleanup on solid-phase extraction cartridges. The procedure was optimized to obtain maximum recovery and minimum signal suppression/enhancement from matrix effects. Analytes were separated with a Phenomenex Gemini-NX C18 analytical column (150 mm × 2.0 mm, 3 μm particle size) using an aqueous methanol gradient at a flow rate of 0.2 mL/min. Column effluent underwent positive electrospray ionization (ESI). Two or more diagnostic product ions were acquired from analyte specific precursor ions for unambiguous confirmation and quantification. The method detection limit was 3.27-4.87 ng/g of particulate matter (PM). Method accuracy, determined with analyte recoveries, ranged between 68% and 117%, and method precision, expressed as relative standard deviation, was below 15% at spiked levels of 6.67, 33.3, and 167 ng/g PM. Analysis of TSP samples demonstrated the presence of the target species associated with PM in the vicinity of beef cattle feeding operations.     

Density and viscosity of 16α,17α-epoxyprogesterone solutions in chloroform

density and viscosity of 16α,17α-epoxyprogesterone solutions in chloroform were determined over the concentration range up to ∼1.9 mol l⁻¹ at temperatures from 287.65 to 321.15 K. The relative viscosity data were correlated using the extended Jones-Dole equation, a good accuracy of the correlation being obtained.     

Simultaneous Determination of Diethylstilbestrol, Testosterone, and 17β-Estradiol Residues in Meat and Meat Products Using Gas–Liquid Chromatography

A gas-chromatographic procedure was developed for the simultaneous determination of hormones (diethylstilbestrol, testosterone, and 17-estradiol) as heptafluorobutyric anhydride derivatives. A mid-polarity HP-50 capillary column (silicone liquid phase containing 50% phenyl groups) and an electron-capture detector were used. The detection limits were 0.3–0.6 mg in a sample of 2 L. The applicability of this procedure for the determination of hormone residues in meat and meat products was demonstrated.     

Synthesis, complexation properties and crystal structure of 4'''',5''''-dibromo-oxylyl-17-crown-5 ether

4',5'-Dibromo-o-xylyl-17-crown-5 ether (2BrB17C5) was synthesized,starting from 1,2-dibromo-4,5-bis(bromomethyl)-benzene and tetraethylene glycol,and was characterized by 1H NMR,MS and elemental analysis.Pale yellow prismatic single crystal obtained from anhydrous ethanol was investigated by X-ray structural analysis.The complexation properties toward alkali metal ions were examined using the solvent extraction method and UV absorption spectroscopy.The crown ether was found to be conformationally deformed and oblate-like and is highly selective for lithium ion.     

Transformed steroids. 185. Use of the Nicholas reaction for regio- and stereo-selective transformation of 16α,17a-epoxy-17Β-ethynyl-androstanes into 16α,17α-cis-disubstituted steroids

The HBF₄·Et₂O-catalyzed methanolysis reactions of the 16, 17-oxides of 17-ethy-nylandrost-4-en-3-one and its dicobalt hexacarbonyl complex were studied. It was shown that these reactions proceed with the same regiodirectivity of the oxide ring opening at the tertiary center but with a different mode of stabilization of the intermediates formed. The reaction of the free oxide proceeds without the inclusion of the external nucleophile and is concluded by the Wagner-Meerwein rearrangement; the C¹⁷-carbocation formed in the Co-coordinated oxide is stabilized by the addition of the methoxide ion and the elimination of a proton or of water. The opening of the oxide ring of dicobalt tetracarbonyl 16, 17-epoxy-17-ethynylandrost-4-en-3-one can be realized with decomplexation accompanied by carbonylation and heterocyclization.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp.1180–1184, May, 1991.     

Reactivity of Hydroxy and Keto Groups on C-6 and C-17 of 3α,5α-Cycloandrostanes

Convenient methods for preparing several 3,5-cycloandrostanes have been developed in order to synthesize the phytoecdysteroid rubrosterone. Certain of their chemical transformations were studied     

High Performance Liquid Chromatographic Separation of Estradiol-17 α and -17/β in Biological Fluids; Application to Plasma,Milk and Urine of Cows

Abstract

A rapid HPLC technique was developed to separate estradiol epimers. In order to improve the sensitivity of the detection, a radioitmmunoassay was used.

Estrone, estradiol-17α and estradiol-17β were separated within 20 min using 10 ml of chloroform: acetone (90:10), as the mobile phase. The efficiency of the technique was assessed with ₃ steroids and the assay of collected fractions with antlsera specific to each estrogen. Using a non-specific radioimmunoassay, profiles of endogenous estrogens in different biological fluids (blood plasma, milk, urine) were obtained.

The efficiency of HPLC as a separation method and the high sensitivity of radioimmunoassay as a detector allows us to obtain profiles of estrogens from biological samples where steroid concentration is below lOOpg/ml.     

Separation of dansylated 17β-estradiol, 17α-estradiol, and estrone on a single HPLC column for simultaneous quantitation by LC–MS/MS

We show here that baseline separation of dansylated estrone, 17β-estradiol, and 17α-estradiol can be done, contrary to previous reports, within a short run time on a single RP-LC analytical column packed with particles bonded with phenyl-hexyl stationary phase. The chromatographic method coupled with isotope dilution tandem MS offers a simple assay enabling the simultaneous analysis of these analytes. The method employs ¹³C-labeled estrogens as internal standards to eliminate potential matrix effects arising from the use of deuterated estrogens. The assay also offers adequate accuracy and sensitivity to be useful for biological samples. The practical applicability of the validated method is demonstrated by the quantitative analyses of in vivo samples obtained from rats treated with Premarin®.

Design,Synthesis, Evaluation and Structure of Allenic 1α,25-Dihydroxyvitamin D3 Analogs with Locked Mobility at C-17

Vitamin D receptor ligands have potential for the treatment of hyperproliferative diseases and disorders related to the immune system. However, hypercalcemic effects limit their therapeutical uses and call for the development of tissue-selective new analogs. We have designed and synthesized the first examples of 1α,25-dihydroxyvitamin D₃ analogs bearing an allenic unit attached to the D ring to restrict the side-chain conformational mobility. The triene system was constructed by a Pd⁰-mediated cyclization/Suzuki-Miyaura cross-coupling process in the presence of an allenic side chain. The allenic moiety was built through an orthoester-Claisen rearrangement of a propargylic alcohol. The biological activity and structure of (22S)-1α,25-dihydroxy-17,20-dien-24-homo-21-nor-vitamin D₃ bound to binding domain of the vitamin D receptor, provide information concerning side-chain conformational requirements for biological activity.     

17O, 13C, and 1H NMR Studies of p–π Conjugation in 2-Substituted 4-Methylene-1,3-dioxolanes and 4-Methyl-1,3-dioxoles

The ¹⁷O NMR spectra of a number of unsaturated 5-membered cyclic acetals, 2-substituted 4-methylene-1,3-dioxolanes and their endocyclic isomers, 4-methyl-1,3-dioxoles, have been recorded. The ¹⁷O NMR chemical shifts, in comparison with those of similarly 2-substituted 1,3-dioxolanes, were used to explore the variation of the strength of p– conjugation in the unsaturated acetals as a function of the nature of substitution at C2. The ¹⁷O NMR shift data reveal that alkoxy substituents have a significantly more favorable effect on the strength of p– conjugation in 4-methyl-1,3-dioxoles than in 4-methylene-1,3-dioxolanes. This fact appears to be responsible for the previously observed unexpectedly large effect of alkoxy substitution on the relative thermodynamic stabilities of these two classes of isomeric compounds. Additional information of the unexpected charge distribution in 4-methyl-1,3-dioxoles is provided by their ¹H and ¹³C NMR spectra.     

Anabolic, doping, and lifestyle drugs, and selected metabolites in wastewater—detection, quantification, and behaviour monitored by high-resolution MS and MS n before and after sewage treatment

Municipal wastewater has been examined for steroids, β₂-agonists, stimulants, diuretics, and phosphodiesterase type V inhibitors (PDE type V inhibitors), which are “dual-use-drugs” applied either as anabolic, doping, and lifestyle drugs or for treatment of diverse diseases. To identify their origin, fitness centre discharges under suspicion of being point sources and sewage-treatment plant feed and effluents were sampled and concentrations determined. Sensitive and selective methods for determination and quantification based on solid-phase extraction (SPE) followed by high-performance liquid chromatography–high resolution mass and tandem mass spectrometry (HPLC–(HR)MS and HPLC–MS–MS) were developed and established for analysis of these compounds in wastewater and to assess their effect on the environment. The methods developed enabled quantification at trace concentrations (limit of quantification (LOQ): 5 ng L⁻¹). Of the steroids and stimulants under investigation, testosterone, methyltestosterone, and boldenone or ephedrine, amphetamine, and MDMA (3,4-methylendioxy-N-methylamphetamine) were observed at up to 5 μg L⁻¹ (ephedrine). Of the β₂-agonists salbutamol only, and of the diuretics furosemide and hydrochlorothiazide were confirmed in the extracts. Quite high concentrations of the PDE type V inhibitors sildenafil, tadalafil, and vardenafil and their metabolites were confirmed in fitness centre discharges (sildenafil: 1,945 ng L⁻¹) whereas their concentrations in municipal wastewater did not exceed 35 ng L⁻¹. This study identified anabolic and doping drugs in wastewater for the first time. Results obtained from wastewater treatment plant effluents proved that these “dual-use-drugs”, with the exception of hydrochlorothiazide, were mostly eliminated.     

Über Heterocyclen, 17. Mitt.

Zusammenfassung Hexahydro-8a-methylpyrimido[4,5-d]pyrimidin-2,7 (1H, 3H)-dione reagieren mit o-reaktiven Phenolen zu Hexahydro-10a-methyl-2H[1]benzopyrano[2,3-d]pyrimidin-2-onen.

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Heterocycles, XVII: Hexahydro-8a-methylpyrimido[4,5-d]-pyrimidine-2,7 (1H, 3H)-diones

Hexahydro-10a-methyl-2H[1]benzopyrano[2,3-d]pyrimidin-2-ones have been synthesized by the reaction of hexahydro-8a-methylpyrimido[4.5-d]pyrimidine-2.7(1H, 3H)-diones with phenols having reactive o-positions.

     

Labeling and Probing the Silica Surface Using Mechanochemistry and 17O NMR Spectroscopy**

In recent years, there has been increasing interest in developing cost-efficient, fast, and user-friendly ¹⁷O enrichment protocols to help to understand the structure and reactivity of materials by using ¹⁷O NMR spectroscopy. Here, we show for the first time how ball milling (BM) can be used to selectively and efficiently enrich the surface of fumed silica, which is widely used at industrial scale. Short milling times (up to 15 min) allowed modulation of the enrichment level (up to ca. 5 %) without significantly changing the nature of the material. High-precision ¹⁷O compositions were measured at different milling times by using large-geometry secondary-ion mass spectrometry (LG-SIMS). High-resolution ¹⁷O NMR analyses (including at 35.2 T) allowed clear identification of the signals from siloxane (Si−O−Si) and silanols (Si−OH), while DNP analyses, performed by using direct ¹⁷O polarization and indirect ¹⁷O{¹H} CP excitation, agreed with selective labeling of the surface. Information on the distribution of Si−OH environments at the surface was obtained from 2D ¹H−¹⁷O D-HMQC correlations. Finally, the surface-labeled silica was reacted with titania and using ¹⁷O DNP, their common interface was probed and Si−O−Ti bonds identified.     

Sixth international symposium on biological and environmental reference materials (BERM-6), Kona,Hawaii, 17–21 April 1994

The present paper lists additional biological and environmental reference samples. Included are three tables that provide an easy-to-use survey. The following information is covered: the name of the material, the sample code, the producer, the reference to certification, the names and addresses of the suppliers from whom the reference material may be obtained, and specific remarks.