Some new ring- seco steroids

The Beckmann fragmentation product, 3-methoxy-17-oxo-16,17-secoestra-1,3,5(10)-trien-16-nitrile (2) has been reduced by LAH giving the expected 3-methoxy-17-hydroxy-16,17-secoestra-1,3,5(10-trien-16-amine hydrochloride (3) and 3-methoxy-17-oxa- -homoestra-1,3,5(10)-trien-16-ol (4), by a presumed neighbouring group participation of 17-OH group in the intermediary formed 16-imino derivative (A). The structure of 4 has been proved by an alternative synthetic route by reducing 3-methoxy-17-oxa- -homoestra-1,3,5(10)-trien-16-one (7) with di-iso-butylaluminium hydride.     

Synthesis and unusual beckmann fragmentation reaction of syn-3-Methoxy-6α,17β-Dihydroxyestra-1,3,5(10)-trien-7-one oxime

Sodium borohydride reduction of anti-3-methoxy-17β-hydroxyestra-1,3,5(10)-trien-6,7-dione 7-oxime (4a) afforded syn-3-methoxy-6α,17β-dihydroxyestra-1,3,5(10)-trien-7-one oxime (5), which in thionyl chloride at −18 °C undenvent Beckmann fragmentation reaction to the unexpected 3-methoxy-6-oxo-17β-hydroxy-6.7-secoestra-1.3.5(10)-trien-7-nitrile (6). A mechanism of this fragmentation process was proposed.     

Structural analysis and biomedical potential of novel salicyloyloxy estrane derivatives synthesized by microwave irradiation

New estrane salicyloyloxy or D-homo derivatives were synthesized under microwave (MW) or conventional heating from estrane precursors and methyl salicylate. The MW technique provides advantages regarding product yield and reaction time, and represents a more environmentally friendly approach than conventional heating. Considering the biomedical potential of estrane compounds, we evaluated the antioxidant activity and cytotoxicity of synthesized estrane derivatives in a series of in vitro tests, as well as their 3β-hydroxysteroid dehydrogenase/Δ⁵ → Δ⁴ isomerase (3βHSD) and 17β-hydroxysteroid dehydrogenase types 1, 2 and 3 (17βHSD1, 17βHSD2 and 17βHSD3) inhibition potentials. In DPPH tests, 3-methoxyestra-1,3,5(10)-trien-17β-yl salicylate displayed antioxidant potential, while all compounds exhibited OH radical neutralization activity. 3-Oxoestr-4-en-17β-yl salicylate showed strong cytotoxicity against MDA-MB-231 breast cancer cells, while 17-oxoestra-1,3,5(10)-trien-3-yl salicylate, estra-1,3,5(10)-triene-3,17β-diyl 3-benzoate 17-salicylate and 3-benzyloxy-17-salicyloyloxy-16,17-secoestra-1,3,5(10)-triene-16-nitrile showed the strongest inhibition of PC-3 prostate cancer cell growth. 3-Hydroxyestra-1,3,5(10)-trien-17β-yl salicylate was the best inhibitor of 17βHSD2, suggesting potential use in treating pathological conditions associated with estrogen depletion. For 3-methoxyestra-1,3,5(10)-trien-17β-yl salicylate and 3-oxoestr-4-en-17β-yl salicylate, X-ray crystal structure analysis and molecular energy optimization were performed to define their conformations and energy minima. Very good overlap in the region of the steroidal nucleus was observed for the molecular structures of each analyzed molecule in the crystalline state and after energy optimization, while conformer analysis indicates conformational flexibility in the form of rotation around the C17···O2 bond. Structural geometry analysis for these compounds shows that the region of ring A in steroids, and especially the C3 atom functional group, is important structural features concerning antiproliferative activity against MDA-MB-231 cells.

     

Enzymatic synthesis and bioactivity of estradiol derivative conjugates with different amino acids

A series of N-protected amino acid-estradiol derivative conjugates have been synthesized by coupling of 17β-aminoestra-1,3,5 (10)-trien-3-ol (1) or 17β-hydrazonoestra-1,3,5 (10)-trien-3-ol (2) with different amino acids via the catalysis of subtilisin Carlsberg in organic solvent. Various factors, including the structure of amino acid residue, different N-protecting groups of amino acids, different esters of carboxyl group and water content of the reaction media that influence the efficiency of enzymatic reactions were systematically studied. In vitro biological activity studies revealed that the binding interactions between estradiol derivative conjugates and estrogen receptor can be affected by the properties of the conjugated amino acid, but the effects of the change in binding properties did not result in changes in biological activities in both MCF-7 and HeLa cell lines.     

The total synthesis and anti-fertility activity of 6-silasteroids

4,4-Dimethyl-6-methoxy-4-sila-1-tetralone (2) was prepared by a modified literature procedure and converted to 3-methoxy-6,6-dimethyl-6-silaestra-1,3,5(10),8,14-pentaen-17β-yl acetate (5c). Catalytic hydrogenation of 5c gave 3-methoxy-6,6-dimethyl-6-silaestra-1,3,5(10),8-tetraen-17β-yl acetate (6b), and its 14-iso- and Δ^{1,3,5(10),8(14)} isomers, the proportions varying with the catalyst and solvent. Reduction of 6b with lithium-liquid ammonia, and O-demethylation, gave 6,6-dimethyl-6-silaestradiol (8b). Reduction of the 3-methyl ether of 8b with lithium-liquid ammonia-t-butanol and hydrolysis afforded 3-keto-6,6-dimethyl-6-silaestr-1(10)-en-17β-ol (15), which was catalytically reduced to its 1,10α-dihydro derivative 17. The 5,6 SiC bond of 8b, 15 and their derivatives was cleaved by boron tribromide, aq. ethanolic hydrogen fluoride, and other reagents, providing a series of 5,6-seco-6,6-dimethyl-6-silasteroids. X-ray crystallographic analysis of 17 and the 17α-ethynyl derivative of 15 confirmed the stereochemical assignments. None of the compounds which were subjected to uterotropic, anti-uterotropic, or post-coital assays, showed significant activity. A partially completed synthesis of 6-silaestradiol (21a) is described.     

Mass spectra of dihydroxy stereoisomers of 3-methoxy-1,3,5(10)-estratrienes

Electron impact mass spectral data for each of the four isomeric 16,17-, 15,17- and 14,17-diols of 3-methoxy-1,3,5(10)-estratriene and the 15,17-diols of 3-methoxy-14β-1,3,5(10)-estratriene are reported. The mass spectra of the diols show very similar fragmentation patterns except for differences in the relative abundances of particular ions. The different [M ? H₂O]⁺˙/[M] ⁺˙ and [M ? 2H₂O] ⁺˙ [M] ⁺˙ ratios can be used for distinguishing between the four isomeric 3-methoxy-1,3,5(10)-estratriene-14,17-diols as well as between the four isomeric 3-methoxy-14β-1,3,5(10)-estratriene-15,17-diols. No significant differences could be detected in the spectra of the epimeric 16,17-and 15,17-diols of 3-methoxy-1,3,5(10)-estratriene.     

Synthesis and molecular structure study of 3-methoxy-7α-methyl-6-oxa-9β,14β-estra-1,3,5(10)-trien-17-one in solution

It was established by NMR spectroscopy that the catalytic hydrogenation of 3-methoxy-7α-methyl-6-oxa-14β-estra-1,3,5(10),8-tetraen-17-one leads to the formation of 3-methoxy-7α-methyl-6-oxa-9β,14β-estra-1,3,5(10)-trien-17-one, the structure of which was investigated in solution. The corresponding analog with a free hydroxyl group at the position 3 possesses an antiradical activity at the absence of uterotropic effect.     

New analogs of steroid estrogens

Aiming at the investigation of the mechanism of functioning of steroid estrogens a series of compounds with unnatural rings junction was synthesized. All investigated compounds exhibit a reduced uterotropic activity. It was established applying the NMR spectroscopy that 7α-methyl-3-methoxy-D-homo-6-oxa-8α,14β-estra-1,3,5(10)-trien-17a-one existed in solution in two conformations distinguished by the structure of the rings B, C, and D simultaneously. The reaction of 17-methylidene-3-methoxy-6-oxa-8α-estra-1,3,5(10)-triene with hydrobromic acid in acetic acid promotes a rearrangement with the migration of a methyl group into the position 17 resulting in the formation of 17,17-dimethyl-6-oxa-8α-gona-1,3,5(10),13(14)-tetraene derivatives.     

Steroide—XL: 16,17-azido- und 16,17-aminoalkohole des östra-1,3,5(10)-trien-3-methyläthers

The four epimeric azido alcohols of estra-1,3,5(10)-trien-3-methyl ether with nitrogen at C-16 and oxygen at C-17 were prepared by the following reactions: cleavage of the 16α,17α-epoxide 1 with sodium azide affords the 16β,17α-azido alcohol 2a. The analogous reaction of the 16β,17β-epoxide 4 gives the 17α,16β-azido alcohol 5a and the desired 16α,17β-azido alcohol 6a in low yield. 6a is obtained in a smooth reaction by substitution of the 16β,17β-bromohydrine 8 with sodium azide. Sodium borohydride reduction of the 16β-azido-17-ketone 9 yields the 16β,17β-azido alcohol 10a, reduction of 16α-azido-17-ketone 13 with lithium borohydride gives the 16α,17α-azido alcohol 14a. From the azido alcohols the corresponding amino alcohols 3a, 7a, 11a and 15a are prepared with hydrazine hydrate/Raney nickel. The amino alcohols give the acetic anhydride the corresponding acetylamino alcohols. The cis-amino alcohols 11a and 15a react with acetone to the corresponding oxazolidines 12 and 16.     

d‐Secoestrone derivatives. V

The two title 16,17‐secoestrone derivatives, 3‐methoxy‐17‐oxo‐17‐phenyl‐16,17‐secoestra‐1,3,5(10)‐triene‐16‐nitrile, C₂₅H₂₇NO₂, (I) (17‐oxo substituent), and 17‐hydroxy‐3‐methoxy‐17‐phenyl‐16,17‐secoestra‐1,3,5(10)‐triene‐16‐nitrile, C₂₅H₂₉NO₂, (II) (17‐hydroxy substituent), have quite different conformations in the solid state. These conformational differences can be minimized by molecular mechanics calculations. Thus, the remarkable difference in the biological activity of the two compounds, e.g. the strong oestrogenic characteristics of (I) and the moderate antioestrogenic action of (II), must be caused by the difference in substitution at C17. In (II), the mol­ecules are linked by O—H?N hydrogen bonds, forming spirals along the b direction.     

Steroide—XLIV : 1H-NMR-untersuchungen. Konfigurationszuordnung 16,17-disubstituierter steroide

¹H-NMR-spectra of 16,17-disubstituted estra-1,3,5(10)-trienes and androstanes are discussed with regard to the determination of the configuration in the positions 16 and 17. The availability of the coupling constant J_16,17, the chemical shift of the 13β-methyl protons, the chemical shift of the 17-proton and both the chemical shift and the sum of the coupling constants of the 16-proton is investigated for the elucidation of unknown configurations at C-16 and C-17. 16β,17α-Configuration of the substituents was found to be distinguished from the other three configurations by a low coupling constant J_16,17 (≦2 Hz). For the determination of the other configurations the coupling constant J_16,17 was also used together with the other data. Esterification of the 17-hydroxy group or its reaction with trichloracetylisocyanate caused a low field shift of the 17-proton depending on the configuration of the substituents in the positions 16 and 17. This is an additional possibility for the configurational assignment.     

High-performance liquid chromatographic methods for monitoring of isomers of 17-hydroxy-16-hydroxymethyl-3-methoxyestra-1,3,5(10)-triene.

Claisen condensation and consecutive reduction of 3-methoxyestra-1,3,5(10)-trien-17-one theoretically leads to four diastereomers of 17-hydroxy-16-hydroxymethyl-3-methoxyestra-1,3,5(10)-triene and their further transformations give different compounds with different biological activities. High-performance liquid chromatographic methods were developed for separation of the four isomers of 17-hydroxy-16-hydroxymethyl-3-methoxyestra-1,3,5(10)-triene: reversed-phase separation on a Nucleosil ODS C18 column with water-methanol as mobile phase; and normal-phase separation on an APEX Silica column with hexane-dichloromethane-2-propanol as mobile phase. The effects of eluent composition and flow-rate on the separation were investigated. This is the first chromatographic evidence for the formation of the 16alpha,17alpha isomer in the reduction of 16-hydroxymethylene-3-methoxyestra-1,3,5(10)-trien-17-one.     

Synthesis of New Estrone Derivatives Using Excess Oxalyl Chloride

The synthesis and structure elucidation of three new estrone derivatives chloro-oxo-acetic acid (estra-1,3,5(10)-trien-17-on-3-yl methyl) ester (2), oxalic acid mono (estra-1,3,5(10)-trien-17-on-3-yl methyl) ester (3), and ethyl (3-methoxyestra-1,3,5(10)-trien)-17-yl oxalate (5) have been described.     

Synthesis of steroid 24,20-lactones by means of phenylselenolactonization

A synthesis of (20 R)- and (20 S)-3β-methoxy-5-cholen-24,20-lactones (7a and 7b) from 3β-methoxy-5-androsten-17-one (2) is described. The 17-ketone 2 was treated with isopropenyllithium to give 3β-methoxy-17α-(prop-l'-en-2'-ylo)-5-androsten-17β-ol (3). Compound 3 on reaction with ethyl orthoacetate and Claisen rearrangement of intermediate 17β-orthoester furnished ethyl esters of (E)- and (Z)-3β-methoxy-chol-5,17(20)-diene-24-acids (4b and 4a). Hydrolysis of ester groups in 4a and 4b and phenylselenolactonization afforded stereospecifically and regioselectively unsaturated (20 R)- and (20 S)-3β-methoxy-chol-5,16-diene-24, 20-lactones(6a and 6b), respectively. Reduction of double bond 16-17 in 6a and 6b gave the final products 7a and 7b. The phenylselenolactonization of(E)- and (Z)-3β-methoxy-chol-5,17(20)-diene-24-acids (5b and 5a) and spontaneous elimination of phenylselenyl moiety was investigated and compared with iodolactonization of the same unsaturated acids.     

Synthesis of <Superscript>131</Superscript>I labeled estrone derivatives and biodistribution studies on rats

Summary The aim of this study is to synthesize novel ¹³¹I labeled estrone derivatives that may have therapeutical potentials on Estrogen Receptor rich tumors. Two radiolabeled estrone derivatives, [¹³¹I]2-iodo-3-methoxy-estra-1,3,5-trien-17-one and [¹³¹I]4-iodo-3-methoxy-estra-1,3,5-trien-17-one were synthesized. Ether amino estrone derivatives were obtained from estrone in three steps by means of diazonium compounds. Tissue distribution studies exhibited receptor-mediated uptake in target organs in female Albino Wistar rats. Maximum uptakes for 2-iodo[¹³¹I]-3-methoxy-estrone are in stomach, pancreas, intestines and uterus. A similar biodistribution profile was obtained for 4-iodo[¹³¹I]-3-methoxy-estrone. However 2-iodo-3-methoxy-estra-1,3,5-trien-17-one has higher uptake in stomach, kidneys, pancreas, and intestines than 4-iodo-derivative.     

Synthesis of 16,17-seco-steroids with iminomethyl-2-pyridine and aminomethylene-2-pyridine structures as chiral ligands for copper ions and molecular oxygen activation

Starting from 16-oximino-3-methoxy-estra-1.3.5(10)-trien-17-one, the 16,17-seco-13α-carbaldehyde with a 16-nitrile function and its corresponding carboxylic acid have been synthesized via a Beckmann fragmentation. The corresponding 13α-amine is available by Curtius degradation of the carboxylic acid. Condensation of the carboxaldehyde with 2-(aminomethyl)pyridine and the primary amine with pyridine-2-carboxaldehyde gave the corresponding iminomethyl-2-pyridine and the aminomethylene-2-pyridine compounds. Copper-mediated ligand hydroxylations with molecular oxygen were not successful. Reasons for this are discussed.     

Synthesis of 5-substituted 2-(4- or 3-methoxyphenyl)-4(1H)-quinolones

5-Substituted 7-methoxy-2-(4- or 3-methoxyphenyl)-4(1H)-quinolones 8-17 have been synthesised in good yields from the corresponding 7-methoxy-2-(4- or 3-methoxyphenyl)-5-trifluoromethanesulfonate-4(1H)-quinolones 7 via palladium-mediated cross-coupling reactions or aromatic nucleophilic substitution (SN_Ar) reactions.     

Steroid derivatives of purine-6(1H)-thione (1a-c)

The products obtained as a result of the alkylation of purine-6(1H)-thione, and 6-alkylthiopurines with steroidal-21-(p-bromobenzenesullonates) (H) and 3-methoxy-16α-bromoestra-1,3,5 (10)-tricne-17-one (IV) is reported. The ratio of 9-alkylated to 7-alkylated purine in the alkylation of 6-methylthiopurine (VI) is presented. The use of the S-diphenylmethylprotecling group in the syntheses of sensitive 9-steroidal-9H-purine-6(1H)-thiones is discussed.     

The 7,8-epoxy-2,3,5,6-tetrakis(methylene) bicyclo[2.2.2]octane; synthesis and diels-alder reactivity

The preparation of 7,8-epoxy-2,3,5,6-tetrakis(methylene)bicyclo[2,2,2] octane (5) is described. Evidence for transannular interaction between the homoconjugated s-cis-butadiene functions in 5 is found in the UV absorption spectrum. The Diels-Alder addition of 5 to tetracyanoethylene (TCE) is syn-regioselective and leads to the monoaducts 16:17 (85:15). The dienes 16,17 are less reactive than 5 toward TCE. anti-regioselectivity (leading to exo-2, endo-3-bis(chloromethyl)-5,6-bis(methylene)-syn-7,8-epoxybicyclo[2.2.2]octaves (25) is observed in the double elimination of HCl from the syn-7,8-epoxy-exo-2,endo-3,exo-5,endo-6-tetrakis(chloromethyl)bicyclo[2.2.2]octane (11), precursor of 5. The structures of the regioisomers 16,17 were confirmed spectroscopically and chemically. Elimination of HCl from the chloromethyl groups in 26 (TCE adduct of 25) and HCN from the TCE adducts 16, 17 and 26 can be induced by CsF in DMF.     

The synthesis of steroidal [16α,17α-d]-2'-pyrazolines and [16,17-d]-pyrazoles

The addition of diphenylnitrilimines to a series of steroidal 16,17-dipolarophiles occurs with the same regio specificity in all cases regardless of the nature of the 17-substituent, to yield [16α, 17α-d]-2'pyrazolines. The adducts from the 17-acetoxy-16,17-androstene, 3c, cannot be isolated but yield the [16,17-d]-pyrazoles by loss of acetic acid.