Mercaptolysis of the E/F Rings of Steroidal Sapogenins:A Concise Synthesis of Δ~(20(22))-Furostene-26-thioethers

Lewis acid catalyzed mercaptolysis of steroidal sapogenins wasreinvestigated. Besides obtaining the reported 26-thioacetals 5under milder conditions, a new type of compounds △~(2O(22))-furostene-26-thioethers 6 were also synthesized through themercaptolysis of steroidal sapogenins, which can be used to thesynthesis of the steroidal molecule with side chains.     

Two New C—21 Steroidal Glycosides from Cynanchum aurichulatum

Two new C-21 steroidal glycosides, cynanauriculoside I and cynanauriculoside Ⅱ, were isolated from the roots of Cynanchum aurichulatum. Their structures were established using spectroscopic methods including one and two-dimensional NMR.     

Intramolecular cyclization of steroidal semicarbazones to pyrazoles using Vilsmeier reagent

The preparation of hitherto unknown steroidal heterocycles containing pyrazole fused to 6,7-position of the steroidal nucleus is described. These heterocycles were prepared by the action of Vilsmeier reagent with steroidal semicarbazones in DMF. The structure of the compounds has been established on the basis of their elemental analysis and spectral data. A general mechanistic scheme for these reactions is also suggested based on current and previous results.     

Three new C21 steroidal glycosides from the roots of Cynanchum inamoenum

Three new C_(21) steroidal glycosides named inamoside E (1),inamoside F (2) and inamoside G (3) were isolated from the roots of Cynanchum inamoenum (Maxim.) Loes.Their structures were determined by spectroscopic analysis,especially by 1D and 2D NMR experiments.     

Facile Synthesis of Ophipogonin C′ and its Three Analogues

Among the huge number of glycoconjuates, the steroidal glycosides are often found as the major components in traditional Chinese medicine. Steroidal glycosides constitute a structurally and biologically diverse class of molecules which have been isolated from a wide variety of both plant and animal species 1. Because of the variety of promising pharmaceutical properties2, the large family of steroidal glycosides has received considerable attention of chemist. Figure 1 OOOOR4R3OR2OOR1O …     

Dracaenoside A and B, New C-22 Steroidal Lactone Glycosides from the Stem of Dracaena cochinchinensis

Two new C-22 steroidal lactone glycosides, named dracaenoside A and B were isolated from the methanol extract of the fresh stem of Dracaena cochinchinensis. Their structures were established as (20S)3β,14α,16β-trihydroxy pregn-5-ene-22-carboxylic acid (22,16)-lactone 3-O-α-L-rhamnopyranosyl (1→2)[ α-L-rhamnopyranosyl (l→4)]-β-D-glucopyranoside and (20S)3β, 14α,16β-trihydroxy pregn-5-ene-22-carboxylic acid (22,16)-lactone 3-O-α-L-rhamnopyranosyl (1→2)[β-D-glucopyranosyl(1→3)]-β-D-glucopyranoside by means of 2D NMR spectral and chemical methods. It is the first time that steroidal lactone glycosides were isolated from the genus Dracaena.     

Two New Spirostanol Steroidal Sapogenins from Fermented Leaves of Agave americana

The genus Agave is well known as rich sources of steroidal saponins and sapogenins 1. More than ten steroidal sapogenins have been isolated from Agave americana L.2-4 In this paper, we describe the structural determination of two new steroidal sapogenins from fermented leaves of A. americana L. The methanolic extracts of dried residues of fermented leaves of A. americana L. produced in Ruili County of Yunnan Province at January 2000, were subjected to repeated column chromatography of …     

A Flexible Approach to the γ－Amino－β－hydroxy Acid Moiety of Hapalosin

A flexible approach to ethyl (3R,4S)-N-Boc-4-amino-3-hydroxy-5-phenylpentanoate (N-Boc-AHPPA-OEt), the γ-amino-β-hydroxy acid moiety of hapalosin is described. The synthetic method features a ring-opening ethanolysis of an activated N-Boc-lactam, which is obtained via a diastereoselective reductive-alkylation of (R)-malimide derivative. The flexibility of the method resides in the introduction of the alkyl side chain by Grignard reagent addition.     

Syntheses and Crystal Structure of Six－coordinated Diorgnotin Complexes with 2,5－Dimercapto－4－phenyl－1,3,4－thiodiazole

The reactions of diorganotin dichloride [Ph_2SnCl_2, (PhCH_2)_2-SnCl_2 or (n-Bu)_2SnCl_2] with potassium salt of 2,5-dimercapto-4-phenyl-1, 3, 4-thiodiazole gave complexes R_2Sn (S_3N_2C_8H_5)_2(4: R=Ph; 5: R=PhCH_2 and 6: R=n-Bu), respectively.Characterizations were carried out for all complexes by IR, ~1HNMR spectra and X-ray crystallography analysis. Including theSn…N interaction, the three complexes all have six-coordinateddistorted octahedral geometry. Based on the requence of stereo-chemical constraint sequence, phenyl≈benzyl>n-butyl, the lessthe effect of the stereochemical constraint of R groups, the     

A New Approach to the Asymmetric Reaction of the Chiron 5－L－Menthyloxy－2（5H）－furanones with Horner－Emmons Reagent

The asymmetric reaction of the chiron 2(5H )-furanones (4a-4c) with the Horner-Emmons reagents (5a-5b) has been investigated. The newly chirai organophosphorus derivatives 6 and 7 were obtained using the phosphoryl-stabilized carbanion as a building block in DMSO under mild conditions. Through the asymmetric introduction, the Horner-Emmons reagent could be transformed to a chiral building block to afford the novel functionalized phosphorus derivatives. The structures of the synthesized compounds 6 and 7 were identified on the basis of their elementary and spectroscopic data, such as IR,^1H NMR, ^13C NMR, MS and X-ray crystallography. These resuits provided a valuable approach to the synthesis of potentially interesting chirai organophosphorus derivatives and probing their biological activities.     

25R/25S stereochemistry of spirostane‐type steroidal sapogenins and steroidal saponins via chemical shift of geminal protons of ring‐F

A method based on the differences among the ¹H NMR chemical shifts of geminal protons of ring‐F methylene resonances (H₂‐23, H₂‐24 and H₂‐26) is proposed for ascertaining the 25R/25S stereochemistry of ring‐F unsubstituted spirostane‐type steroidal sapogenins and steroidal saponins. Copyright © 2003 John Wiley & Sons, Ltd.     

Study on steroidal saponins in crude and stir‐fried Fructus Tribuli by ultra‐high‐performance liquid chromatography‐mass spectrometry coupled with multivariate statistical analysis

Fructus Tribuli is a traditional Chinese medicine used clinically for many years. Crude Fructus Tribuli and stir‐fried Fructus Tribuli are recorded in the Pharmacopoeia of the People′s Republic of China. However, the differences between steroidal saponins in crude Fructus Tribuli and stir‐fried Fructus Tribuli have not been compared. In this study, ultra‐high‐performance liquid chromatography quadrupole time‐of‐flight mass spectrometry along with multivariate statistical analysis was developed to discriminate the chemical profiles and identify the steroidal saponins of crude Fructus Tribuli and stir‐fried Fructus Tribuli. Additionally, an ultra‐high‐performance liquid chromatography triple‐quadrupole mass spectrometer was used for the simultaneous quantification of nine major steroidal saponins to analyze the variations between crude Fructus Tribuli and stir‐fried Fructus Tribuli. Finally, a total of 30 steroidal saponins whose structures or contents changed significantly after processing were found and identified. The mechanism of structural transformations deduced indicated that during the stir‐frying of Fructus Tribuli, C‐22 hydroxy furostanol saponins were converted to the corresponding furostanol saponins containing C‐20‐C‐22 double bonds by dehydroxylation and deglycosylation reactions that occurred in the spirostanol saponins causing the generation of steroidal sapogenins. This study was successfully applied to the global analysis of crude Fructus Tribuli and stir‐fried Fructus Tribuli. The results of this research will be beneficial to explore the processing mechanism of Fructus Tribuli.     

Novel Steroidal (6R)‐Spiro‐1,3,4‐thiadiazoline Derivatives as Anti‐bacterial Agents

Novel steroidal (6R)‐spiro‐1,3,4‐thiadiazoline derivatives have been synthesized by the cyclization of steroidal thiosemicarbazones. Thiosemicarbazones have been synthesized by the reaction of steroidal ketones with thiosemicarbazide. All the compounds have been characterized by IR, ¹H NMR, mass and elemental analyses. The antibacterial activities of these compounds have been first tested in vitro by the disk diffusion assay against two Gram‐positive and two Gram‐negative bacteria, and then the minimum inhibitory concentration (MIC) values have been determined with the reference of standard drug amoxicillin. The results showed that steroidal thiadiazoline derivatives exhibited better antibacterial activity than the steroidal thiosemicarbazone derivatives. Chloro and acetoxy substituents on the 3β‐position of the steroidal thiadiazoline ring increased the anti‐bacterial activity. Among all the compounds, compounds 7 and 8 were found better inhibitors as compared to the respective drug amoxicillin.     

Synthesis and In Vitro Antibacterial Activity of Novel Steroidal (6R)‐Spiro‐1,3,4‐thiadiazoline Derivatives

Novel steroidal (6R)‐spiro‐1,3,4‐thiadiazoline derivatives were synthesized by the cyclization of steroidal thiosemicarbazones with acetic anhydride, screened in vitro against antibacterial activity using disc‐diffusion method and the minimum inhibitory concentration. The results showed that steroidal thiadiazoline derivatives exhibited better antibacterial activity than the steroidal thiosemicarbazone derivatives. Chloro and acetoxy substituents on the 3β‐position of the steroidal thiadiazoline ring increased the antibacterial activity. Among all the compounds, compound 7 and 8 were found better inhibitors of both types of bacteria (Gram‐positive and Gram‐negative) as compared to the respective drug amoxicillin. All the synthesized compounds were well characterized by spectroscopic methods such as IR, ¹H‐NMR, ¹³C‐NMR mass, and elemental analysis and their stereochemistry was also discussed.     

A two‐dimensional cadmium(II) coordination polymer constructed from 4‐carboxy‐1‐(4‐carboxylatobenzyl)‐2‐propyl‐1H‐imidazole‐5‐carboxylate and 1‐(4‐carboxylatobenzyl)‐2‐propyl‐1H‐imidazole‐4‐carboxylate ligands

Crystals of poly[[aqua[μ₃‐4‐carboxy‐1‐(4‐carboxylatobenzyl)‐2‐propyl‐1H‐imidazole‐5‐carboxylato‐κ⁵O¹O^1′:N³,O⁴:O⁵][μ₄‐1‐(4‐carboxylatobenzyl)‐2‐propyl‐1H‐imidazole‐4‐carboxylato‐κ⁷N³,O⁴:O⁴,O^4′:O¹,O^1′:O¹]cadmium(II)] monohydrate], {[Cd₂(C₁₅H₁₄N₂O₄)(C₁₆H₁₄N₂O₆)(H₂O)]·H₂O}_n or {[Cd₂(Hcpimda)(cpima)(H₂O)]·H₂O}_n, (I), were obtained from 1‐(4‐carboxybenzyl)‐2‐propyl‐1H‐imidazole‐4,5‐dicarboxylic acid (H₃cpimda) and cadmium(II) chloride under hydrothermal conditions. The structure indicates that in‐situ decarboxylation of H₃cpimda occurred during the synthesis process. The asymmetric unit consists of two Cd²⁺ centres, one 4‐carboxy‐1‐(4‐carboxylatobenzyl)‐2‐propyl‐1H‐imidazole‐5‐carboxylate (Hcpimda²⁻) anion, one 1‐(4‐carboxylatobenzyl)‐2‐propyl‐1H‐imidazole‐4‐carboxylate (cpima²⁻) anion, one coordinated water molecule and one lattice water molecule. One Cd²⁺ centre, i.e. Cd1, is hexacoordinated and displays a slightly distorted octahedral CdN₂O₄ geometry. The other Cd centre, i.e. Cd2, is coordinated by seven O atoms originating from one Hcpimda²⁻ ligand and three cpima²⁻ ligands. This Cd²⁺ centre can be described as having a distorted capped octahedral coordination geometry. Two carboxylate groups of the benzoate moieties of two cpima²⁻ ligands bridge between Cd2 centres to generate [Cd₂O₂] units, which are further linked by two cpima²⁻ ligands to produce one‐dimensional (1D) infinite chains based around large 26‐membered rings. Meanwhile, adjacent Cd1 centres are linked by Hcpimda²⁻ ligands to generate 1D zigzag chains. The two types of chains are linked through a μ₂‐η² bidentate bridging mode from an O atom of an imidazole carboxylate unit of cpima²⁻ to give a two‐dimensional (2D) coordination polymer. The simplified 2D net structure can be described as a 3,6‐coordinated net which has a (4³)₂(4⁶.6⁶.8³) topology. Furthermore, the FT–IR spectroscopic properties, photoluminescence properties, powder X‐ray diffraction (PXRD) pattern and thermogravimetric behaviour of the polymer have been investigated.     

Syntheses,antitumor activities,and antiangiogenesis of exo‐3,6‐epoxy‐1,2,3,6‐tetrahydrophthalimidoethanoyl‐ 5‐fluorouracil and its polymers

A new monomer, exo‐3,6‐epoxy‐1,2,3,6‐tetrahydrophthalimidoethanoyl‐5‐fluorouracil (ETFU), was synthesized by the reaction of exo‐3,6‐epoxy‐1,2,3,6‐tetrahydrophthalimidoethanoyl chloride (ETPC) and 5‐fluorouracil (5‐FU). The homopolymer of ETFU and its copolymers with acrylic acid (AA) and vinyl acetate (VAc) were prepared via photopolymerizations with 2,2‐dimethoxy‐2‐phenylacetophenone at 25 °C for 48 h. The structures of the synthesized monomer and polymers were identified by Fourier transform infrared, ¹H NMR, and ¹³C NMR spectroscopy and elemental analysis. The ETFU contents in poly(ETFU‐co‐AA) and poly(ETFU‐co‐VAc) were 26 mol % and 26 mol %, respectively. The number‐average molecular weights of the polymers, as determined by gel permeation chromatography, ranged from 5600 to 17,000. The in vitro cytotoxicities of 5‐FU and the synthesized samples against mouse mammary carcinoma and human histiocytic lymphoma cancer cell lines increased in the following order: ETFU > 5‐FU > poly(ETFU‐co‐AA) > poly(ETFU) > poly(ETFU‐co‐VAc). The in vivo antitumor activities of the polymers against Balb/C mice bearing the sarcoma 180 tumor cells were greater than those of 5‐FU at all doses tested. The inhibitions of the samples for SV40 DNA replication and antiangiogenesis were much greater than the inhibition of the control. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4272–4281, 2000     

Synthesis,Spectroscopic, and X‐Ray Diffraction Studies of cis‐Dichlorobis(4‐propanoyl‐2,4‐dihydro‐5‐methyl‐2‐phenyl3 H‐pyrazol‐3‐onato) Tin(IV)

Reaction between an aqueous ethanol solution of tin(II) chloride and that of 4‐propanoyl‐2,4‐dihydro‐5‐methyl‐2‐phenyl‐3 H‐pyrazol‐3‐one in the presence of O₂ gave the compound cis‐dichlorobis(4‐propanoyl‐2,4‐dihydro‐5‐methyl‐2‐phenyl‐3 H‐pyrazol‐3‐onato) tin(IV) [(C₂₆H₂₆N₄O₄)SnCl₂]. The compound has a six‐coordinated Sn^IV centre in a distorted octahedral configuration with two chloro ligands in cis position. The tin atom is also at a pseudo two‐fold axis of inversion for both the ligand anions and the two cis‐chloro ligands. The orange compound crystallizes in the triclinic space group P 1 with unit cell dimensions, a = 8.741(3) Å, b = 12.325(7) Å, c = 13.922(7) Å; α = 71.59(4), β = 79.39(3), γ = 75.18(4); Z = 2 and D_x = 1.575 g cm^–3. The important bond distances in the chelate ring are Sn–O [2.041 to 2.103 Å], Sn–Cl [2.347 to 2.351 Å], C–O [1.261 to 1.289 Å] and C–C [1.401 Å] the bond angles are O–Sn–O 82.6 to 87.7° and Cl–Sn–Cl 97.59°. The UV, IR, ¹H NMR and ¹¹⁹Sn Mössbauer spectral data of the compound are reported and discussed.     

Microwave‐Assisted Synthesis of β‐Lactams and Cyclo‐β‐dipeptides

Different cyclo‐β‐dipeptides were prepared from corresponding N‐substituted β‐alanine derivatives under mild conditions using PhPOCl₂ as activating agent in benzene and Et₃N as base. To evaluate β³‐substituent influence, the amino acids 7 – 26 were synthesized, and a β‐lactam formation reaction was carried out instead of cyclo‐β‐dipeptide formation. The crystal structures of three derivatives of cyclo‐β‐peptides and one β‐lactam are presented.     

Design,Synthesis, and Insecticidal Activity of 1,5‐Diphenyl‐1‐pentanone Analogues

Three series of novel 1,5‐diphenyl‐1‐pentanone derivatives were designed and synthesized. Their structures were characterized by IR, ¹H NMR techniques, and elemental analysis. The insecticidal activities of the new compounds were preliminarily evaluated. The bioassay results indicated that the compounds X11 – X30 displayed better aphicidal activity against Aphis gossypii than compounds X1 – X10 and the lead compound (E)‐1,5‐diphenyl‐1‐penten‐1‐one ( A ). The inhibitory rates of compounds X6 and X29 were 100% against Plutella xylostella (L.) at 600 mg·L^?1. Compounds X12 , X13, X19 , X24, X25 , X26 and X27 showed higher insecticidal activity against Tetranychus cinnabarinus (Boisduval) at 600 mg·L^?1 than the lead compound ( A ).     

High‐quality poly[2‐methoxy‐5‐(2′‐ethylhexyloxy)‐p‐phenylenevinylene] synthesized by a solid–liquid two‐phase reaction: Characterizations and electroluminescence properties

Poly[2‐methoxy‐5‐(2′‐ethylhexyloxy)‐p‐phenylenevinylene] (MEH‐PPV) with a molar mass of 26–47 × 10⁴ g mol^?1 and a polydispersity of 2.5–3.2 was synthesized by a liquid–solid two‐phase reaction. The liquid phase was tetrahydrofuran (THF) containing 1,4‐bis(chloromethyl)‐2‐methoxy‐5‐(2′‐ethylhexyloxy)benzene as the monomer and a certain amount of tetrabutylammonium bromide as a phase‐transfer catalyst. The solid phase consisted of potassium hydroxide particles with diameters smaller than 0.5 mm. The reaction was carried out at a low temperature of 0 °C and under nitrogen protection. No gelation was observed during the polymerization process, and the polymer was soluble in the usual organic solvents, such as chloroform, toluene, THF, and xylene. A polymer light‐emitting diode was fabricated with MEH‐PPV as an active luminescent layer. The device had an indium tin oxide/poly(3,4‐ethylenedioxylthiophene) (PEDOT)/MEH‐PPV/Ba/Al configuration. It showed a turn‐on voltage of 3.3 V, a luminescence intensity at 6.1 V of 550 cd/m², a luminescence efficiency of 0.43 cd/A, and a quantum efficiency of 0.57%. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3049–3054, 2004