An efficient synthesis of optically active (2R,3R)-2-methyl-3-[(1R)-1-methylprop-2-enyl]cyclopentanone, a useful chiral building block for synthesis of vitamin D and steroids

An efficient synthesis of optically active (2R,3R)-2-methyl-3-[(1R)-1-methylprop-2-enyl]cyclopentanone, a useful chiral building block for synthesis of vitamin D and steroids, has been developed starting from readily accessible optically active secondary propargyl phosphate (R)-2, where the asymmetric Michael addition of a chiral allenyltitanium to alkylidenemalonate 3 is a key reaction.     

Highly stereoselective claisen rearrangement of vinyl ether of 1-(1-hydroxyethyl)-2-methyl-3-alkylcyclopentene. A route to cis- and trans (1E)-ethylidene-8-methylhydrindan-5-one.

The highly stereoselective Claisen rearrangement of the α-isomer of vinyl ether of 1-(1-hydroxyethyl)-2-methyl-3-alkylcyclopentene introduces the trans stereochemistry between C(8)methyl and C(9) hydrogen and the geometry of E-olefin, necessary for a synthetic precursor of various steroids. The β-isomer gives the cis stereochemistry.     

Studies on Wittig rearrangement of furfuryl ethers in steroidal side chain synthesis

Wittig rearrangement of 17(20)-ethylidene-16-furfuryloxy steroids 5-8 was examined. Reaction of 17E(20)-ethylidene-16α-furfuryloxy steroid 5 with t-BuLi in THF afforded (20S,22S)- and (20S,22R)-22-hydroxy steroids 9, 10 and 17Z(20)-ethylidene-16α-(2-furyl)hydroxymethyl steroid 11 in 61, 28, and 9% yields, respectively. Base treatment of 17E(20)-ethylidene-16β-furfuryloxy steroid 7 gave (20R,22R)-22-hydroxy steroid 13 and 17Z(20)-ethylidene-16β-(2-furyl) hydroxymethyl steroid 14 in 60 and 17% yields. In contrast, 17Z(20)-ethylidene-16-furfuryloxy steroids 6, 8 led to the corresponding 2,3-rearranged products in low yields (25% for (20R,22S)-22-hydroxy steroid 12; 31% for (20S,22R)-22-hydroxy steroid 10). Both (20S,22S)- and (20S,22R)-22-hydroxy steroids 9, 10 were converted by catalytic hydrogenation into known compounds 16, 17, key intermediates for the synthesis of biologically active steroids.     

Biotransformations of steroids to testololactone by a multifunctional strain Penicillium simplicissimum WY134-2

The biotransformations of a range of steroidal compounds, including 17α-hydroxy progesterone, progesterone, testosterone, androst-4-ene-3,17-dione (AD), pregnenolone, and dehydroepiandrosterone (DHEA), by Penicillium simplicissimum WY134-2 have been investigated. In all the cases, testolic acid and testololactone were detected, and the acid was converted to the lactone when pH was adjusted to 1, leading to isolation of testololactone in 25%–96% yields. Especially for progesterone and testosterone, the isolated yields were 93% and 96% with substrate concentration being 3 g/L, suggesting that P. simplicissimum WY134-2 may be used for the synthesis of testololactone. The results revealed the multi-functional catalytic activity of P. simplicissimum WY134-2 toward steroids for the first time. The possible reaction pathways of steroids promoted by this strain were discussed.     

Fluorescence determination of steroidal dienones

Reaction of Δ^1,4-3-keto steroids with zinc and acid produces a characteristic fluorescence. Estrogenic, 3-keto and Δ⁴-3-keto steroids did not yield this fluorescence. Stabilization of the dienone fluorescence by extraction into butyl ether allowed quantitation of triamcinolone acetonide in liquid formulations in which this dienone was present at the 0.01% level. A mechanism for the reaction is proposed.     

Functionalized enamines—XXII : Annelation of enamines of polycyclic α,β-unsaturated ketones; a facile partial synthesis of furano- indolo- and benzsteroids. Total synthesis of 3-oxa-A-norsteroid

Reaction of dienamine 4a with substituted phenacyl bromides gave steroidal[3,4-b] furans 5a–g. The same principle reaction was utilized for the total synthesis of (±) 2 - (p - chlorophenyl) - 3 - oxa - A - nor - estra - 1,5(10), 9(11) - triene - 17 - acetate 12a. Treatment of 4a, b with benzenediazonium salts, in DMF, followed by a Fischer-indole cyclization yielded steroidal[6, 7-b] indoles 8a–k. Dienamine 4b could be annelated to benz[4, 5, 6] steroids 9a and 9b by reaction with methyl vinyl ketone and crotonaldehyde, respectively.     

Réductions microbiologiques stéréosélectivés des Δ-4 céto-3 stéroïdes

In anaerobic conditions the reduction of Δ-4 3-keto steroids by Clostridium paraputrificum leads either to the 3-keto 5β compounds or to the corresponding 3α-hydroxytetrahydro-5β derivatives. This stereospecific bioconversion of αβ-unsaturated 3-keto steroids is shown to be directed by the substrate concentration. The conversion of Δ-4 cholestenone to coprostanone or coprostanol is not observed.     

Nitrogenous sesquiterpenes from the Thai marine sponge Halichondria sp.

Five nitrogenous sesquiterpenes having an isonitrile [(−)-axisonitrile-3], a formamide [(+)-axamide-3, axamide-2 and (3S^*,5R^*,6R^*,9R^*)-3-formamido-1(10)-cadinene], and an amine [(−)-halichamine] functionality were isolated from the Thai marine sponge Halichondria sp., together with two steroids, ergosterol and ergosterol peroxide. (−)-Axisonitrile-3 was isolated from the natural source for the first time, while (+)-axamide-3 and (−)-halichamine were new metabolites. The structures of these compounds were elucidated on the basis of their spectroscopic data and by chemical transformations. All sesquiterpenes were tested for their cytotoxic activity against six cancer cell lines (HeLa, HuCCA-1, A549, MOLT-3, HepG2, MDA-MB231). Only (−)-axisonitrile-3 showed strong activity to the HepG2 cell line with an IC₅₀ value of 1.3 μM.     

Synthesis of N,N-bis[2-(2-pyridyl)ethyl]amino steroids and related compounds intended as chiral ligands for copper ions

Compounds with the N,N-bis[2-(2-pyridyl)ethyl]amino structure (RPY2) are useful tridentate ligands for copper(I) ions, which can bind and activate oxygen from the atmosphere. For diastereoselective and enantioselective oxidation reactions, hitherto unknown chiral ligands possessing tripodal structures have been synthesized starting from homochiral steroids. The double Michael addition of primary steroidal amines and aminoalcohols to 2-vinyl pyridine was not very succesful. However, homochiral bidentate ligands with N-[2-(2-pyridyl)ethyl]amino steroid structure could be obtained by this procedure in most cases. New routes (acylation of the bidentate ligands with 2-pyridylacetic acid followed by BH₃·THF reduction, or reductive amination of steroidal ketones, acylation and borane reduction) to the desired tridentate RPY2, also at sterically hindered positions, are described. In the last reaction sequence, ‘mixed’ tridentate ligands can also be obtained. Copper complexation and oxygen activation with these ligands are briefly discussed.     

Transformed steroids—part 95 : High pressure induced 1,3-dipolar cycloaddition of nitronic esters to 16-dehydro-20-oxo steroids

High pressure induced cycloaddition of Z and E nitronic esters (2) to 16-dehydro-20-oxo steroids (1) leads to regiospecific formation of steroido [16α,17α-d] tetrahydro-l',2'-oxazoles (3 and 4). It is shown that both modes (“exo-endo”) of dipolarophile approach to the dipole are realized for most steroids examined. All four possible isomers are isolated and their preferred conformations are established. It is shown that conversion of unstable stereomers to stable ones (3'→ 4; 4'→ 3) proceeds as a simultaneous nitrogen inversion and isoxazolidine cycle conformational change (_NE→E^N).     

Complexation and Sensing Behavior of Dansyl-appended Cyclodextrins and Cyclodextrin Dimers with Bile Salts

The dansyl-modified cyclodextrin derivatives 2 and 3 form complexes with the steroidal bile salts. The selectivity of the monomeric derivative 3 is similar to that of native g -cyclodextrin. All binding constants with 3 are lowered compared to g -cyclodextrin because of the competition for the cavity between the steroids and the dansyl moiety. Cholate ( 4a ) and deoxycholate ( 4b ) form weak complexes, the other bile salts ( 4c - e ) are complexed far more strongly. The difference is attributed to the absence of a 12-hydroxy group in the latter steroids. Data for dimer 2 reveal strongly enhanced binding of 4a and 4b and only slightly stronger complexes with the other steroids. Due to the low binding affinity of 3 for 4a and 4b , this receptor could not be used for their detection by fluorescence spectroscopy. Steroids 4c - e showed a decrease in fluorescence intensity. The detection of all steroids 4a - e was possible using 2 . The fluorescence intensity of the dimer increased or decreased, depending on which steroid was added.     

External calibration in gas chromatography-combustion-isotope ratio mass spectrometry measurements of endogenous androgenic anabolic steroids in sports doping control

An alternative calibration procedure for the Gas Chromatography–Combustion–Isotope Ratio Mass Spectrometry (GC–C–IRMS) measurements of the World Antidoping Agency (WADA) Accredited Laboratories is presented. To alleviate the need for externally calibrated CO₂ gas for GC–C–IRMS analysis of urinary steroid metabolites, calibration using an external standard mixture solution of steroids with certified isotopic composition was investigated. The reference steroids of the calibration mixture and routine samples underwent identical instrumental processes. The calibration standards bracketed the entire range of the relevant δ¹³C values for the endogenous and exogenous steroids as well as their chromatographic retention times. The certified δ¹³C values of the reference calibrators were plotted in relation to measured m/z¹³CO₂/¹²CO₂ (i.e. R(45/44)) mass spectrometric signals of each calibrator. δ¹³C values of the sample steroids were calculated from the least squares fit through the calibration curve. The effect of the external calibration on δ¹³C values, using the same calibration standards and set of urine samples but different brands of GC–C–IRMS instruments, was assessed by an interlaboratory study in the WADA Accredited Laboratories of Sydney, Australia and Athens, Greece. Relative correspondence between the laboratories for determination of androsterone, etiocholanolone, 5β-androstane-3α,17β-diacetate, and pregnanediacetate means were SD(δ¹³C) = 0.12‰, 0.58‰, −0.34‰, and −0.40‰, respectively. These data demonstrate that accurate intralaboratory external calibration with certified steroids provided by United States Antidoping Agency (USADA) and without external CO₂ calibration is feasible and directly applicable to the WADA Accredited Laboratories for the harmonization of the GC–C–IRMS measurements.     

A xanthone and a polyketide derivative from the leaves of Cassia obtusifolia (Leguminosae)

A new xanthone, 1,8-dihydroxy-3-methoxy-6-methylxantone and a new polyketide derivative, (4R^∗,5S^∗,6E,8Z)-ethyl-4-((E)-but-1-enyl)-5-hydroxypentdeca-6,8-dienoate, together with 20 known secondary metabolites, including 2 steroids, 4 xanthones, 10 anthraquinones, 2 triterpenoids, 1 fatty ester, and (E)-eicos-14-enoic acid, were isolated from the leaves of Cassia obtusifolia. To the best of our knowledge, the last compound was isolated from a natural source for the first time. The structures of all the compounds were elucidated on the basis of 1D and 2D NMR experiments. Some of the compounds were tested against Salmonella typhi, Staphylococcus aureus, Candida albicans ATCC 9002, and Candida tropicalis, they did not show any activity.     

Topsentiasterol sulfates with novel iodinated and chlorinated side chains from the marine sponge Topsentia sp.

Three new marine polar steroids, the first chlorine-containing steroid sulfate (1), topsentiasterol sulfate F (2) and the first natural iodinated steroid (3) have been isolated from the marine sponge Topsentia sp. The structures of 1-3 were elucidated using NMR and HRESIMS as well as by chemical correlation of 1 with previously known topsentiasterol sulfate D. Compound 1 proved to be an effective inhibitor of endo-1,3-β-d-glucanase from the marine mollusc Spisula sachalinensis.     

New synthetic corticosteroids inhibit Epstein–Barr virus release

Novel spiroandrostene-17,6'-[1,3,4]thiadiazines obtained by synthesis from 16β,17β-epoxy-17-isopregn-5-en-3β-ol-20-one and N-aryl-2-hydrazino-2-thioxoacetamide efficiently inhibited the release of Epstein–Barr virus from cells carrying the virus in culture. Other studied steroids, such as Spirolactone, Digitonin, Diosgenin, and Hecogenin were inactive. DMSO alone was found to inhibit the virus release, as well, likely, because of changing properties of the cell membranes. The novel steroids, Spironolactone and most analogues display no or low cell toxicity while Digitonin produced a significant toxic effect.     

Enantioselective synthesis of 11-substituted 2- or 3-methoxy-17-vinylgona-1,3,5(10)-trien-13-ols

The acylation of the (±)-spiro-γ-lactone 1 lithium enolate (3 equiv) by the O-TBDMS methyl (−)-(S)-lactate, the O-TBDMS methyl (+)-(S)-mandelate, or the diacetone-d-glucose carbonate (1 equiv each) occurs with a kinetic resolution. The (S,S)-enolate is the most reactive with the lactate and it is the (R,R)-enolate, which selectively reacts with the mandelate or the DAG carbonate. After alkylation of the resulting acyl lactones with 4- or 5-methoxy-1-iodobenzocyclobutene and heating, title compounds were obtained and, after deprotection, the structures of the optically pure new steroids were ascertained by single crystal X-ray analysis.     

Five-membered 2,3-dioxo heterocycles: XCVIII. [4 + 2]-cycloaddition of alkyl vinyl ethers to 3-aroyl-1H-pyrrolo[2,1-c][1,4]benzoxazine-1,2,4-triones. A new synthetic approach to heteroanalogs of 13(14→8)-abeo steroids

3-Aroyl-1H-pyrrolo[2,1-c][1,4]benzoxazine-1,2,4-triones reacted with alkyl vinyl ethers according to the [4 + 2]-cycloaddition pattern with formation of substituted (1S*,16R*)- and (1R*,16R*)-16-alkoxy-14-aryl-3,15-dioxa-10-azatetracyclo[8.7.0.0^1,13.0^4,9]heptadeca-4,6,8,13-tetraene-2,11,12-triones. The structure of (1S*,16R*)-7-chloro-16-ethoxy-14-phenyl-3,15-dioxa-10-azatetracyclo[8.7.0.0^1,13.0^4,9]heptadeca-4,6,8,13-tetraene-2,11,12-trione was determined by X-ray analysis. A new synthetic approach was developed to heteroanalogs of 13(14→8)-abeo steroids, substituted 3,15-dioxa-10-azatetracyclo[8.7.0.0^1,13.0^4,9]heptadecanes.     

Analysis of anabolic androgenic steroids in urine by full-capillary sample injection combined with a sweeping CE stacking method

This study describes an on-line stacking CE approach by sweeping with whole capillary sample filling for analyzing five anabolic androgenic steroids in urine samples. The five anabolic steroids for detection were androstenedione, testosterone, epitestosterone, boldenone, and clostebol. Anabolic androgenic steroids are abused in sport doping because they can promote muscle growth. Therefore, a sensitive detection method is imperatively required for monitoring the urine samples of athletes. In this research, an interesting and reliable stacking capillary electrophoresis method was established for analysis of anabolic steroids in urine. After liquid–liquid extraction by n-hexane, the supernatant was dried and reconstituted with 30 mM phosphate buffer (pH 5.00) and loaded into the capillary by hydrodynamic injection (10 psi, 99.9 s). The stacking and separation were simultaneously accomplished at ?20 kV in phosphate buffer (30 mM, pH 5.0) containing 100 mM sodium dodecyl sulfate and 40 % methanol. During the method validation, calibration curves were linear (r?≥?0.990) over a range of 50–1,000 ng/mL for the five analytes. In the evaluation of precision and accuracy for this method, the absolute values of the RSD and the RE in the intra-day (n?=?3) and inter-day (n?=?5) analyses were all less than 6.6 %. The limit of detection for the five analytes was 30 ng/mL (S/N?=?5, sampling 99.9 s at 10 psi). Compared with simple MECK, this stacking method possessed a 108- to 175-fold increase in sensitivity. This simple and sensitive stacking method could be used as a powerful tool for monitoring the illegal use of doping.     

Structures of cyclootochilone and otochilone,two novel steroidal ketones of the orchids otochilusporecta and otochilusfusca

Cyclootochilone and otochilone, two novel steroidal ketones of the orchids Otochilusporecta were shown to have the structures 1a and 2, respectively, from spectral and chemical evidence, 1a alone has also been obtained from the taxonomically related orchid Otochilusfusca. The significance of these compounds in the biogenetic transformation of lanosterol to steroids and the biogenetic sequence of the origin of 9,19- cyclopropane ring present in some terpenoids and steroids, as well as the mechanism of incorporation of two methyl groups at C-24 of some of these compounds were discussed.     

Novel steroids from the soft coral Nephthea chabrolii

Three new metabolites including two new steroids, chabrolosteroids A and B (1 and 2), and a novel spirosteroid chabrolosteroid C (3), were isolated from the organic extract of a Taiwanese soft coral Nephthea chabrolii. The structures of these metabolites were elucidated by extensive spectroscopic analysis and by comparison of the spectral data with those of related steroids. This is the first report of a steroid with a spiro-ring A, B system in natural products.