Possible conformations and relative stability of the 7-membered ring in 1α,5β,6,7α(H)-and 1β,5α,6,7α(H)-guai-11(13)-en-6,12-olides

Stereoisomers of 1,5,6,7(H)- and 1,5,6,7(H)-guai-11(13)-en-6,12-olides are calculated using molecular mechanics. The possibility of forming various conformations in the 7-membered ring is examined as a function of the fusion to the 5-membered C-ring. The effect of the methyl orientation on the conformation of the 7-membered ring and the relative stability of the conformers are discussed.Insitute of Phytochemistry, Karaganda, fax (3212)-43-37-73. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 54–56, January–February, 2000.     

Synthesis of 6-chloronicotinates of steroidal 3β,5α,6β-triols and 3β,5-dihydroxy-6-ketones

New esters of 3β,5α,6β-trihydroxysteroids and 3β,5-dihydroxy-6-ketosteroids containing 6-chloropyridine groups characteristic of the alkaloid epibatidine were synthesized by acylation with 6-chloronicotinoylchloride. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 175-179, March-April, 2009.     

A Facile Synthesis of (-)-5_αH,7β,10_α-Eudesmane-3,1 1-diene

ＡＦａｃｉｌｅＳｙｎｔｈｅｓｉｓｏｆ（－）－５_αＨ，７β，１０_α－Ｅｕｄｅｓｍａｎｅ－３，１１－ｄｉｅｎｅ￥ＮｉｎｇＺＯＵ；ＤｏｎｇＬｉａｎｇＣＨＥＮＧ；ＸｉｎＦｕＰＡＮ；ＹａｏＺｕＣＨＥＮ（ＤｅｐａｒｔｍｅｎｔｏｆＣｈｅｍｉｓｔｒｙ，Ｌａｎｚｈｏ...     

Unusual oxidation reactions of 7α-methyl- and 7α-phenylcholest-5-ene-3β,7β-diol

Summary Ozonation of 7-methyl (or 7-phenyl) cholest-5-ene-3,7-diol 3-TBDMS ether afforded the corresponding 5,6-epoxy derivatives. The same product was formed byMCPBA oxidation. The reaction of 7-phenylcholest-5-ene-3,7-diol with CrO₃ yielded 3,7-dioxo-6,7-seco-7-phenylcholest-4-ene-5-carboxaldehyde. An analogous B-seco aldehyde was obtained from 7-methylcholest-5-ene-3,7-diol in addition to 7-methylcholesta-4,6-dien-3-one.Jones oxidation of 7-phenylcholest-5-ene-3,7-diol or B-seco-aldehyde gave 3,7-dioxo-6,7-seco-7-phenylcholest-4-en-6-oic acid isolated as its methyl ester upon treatment with diazomethane.

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Ungewöhnliche Oxidation von 7-Methyl- und 7-Phenylcholest-3-en-3,7-diol

Zusammenfassung Ozonolyse von 7-Methyl- bzw. 7-Phenyl-cholest-3-en-3,7-diol-3-TBDMS-ether ergab die entsprechenden 5,6-Epoxy-Derivate.MCPBA-Oxidation führte zum gleichen Ergebnis. Bei der Reaktion von 7-Phenyl-cholest-5-en-3,7-diol mit CrO₃ wurde 3,7-Dioxo-6,7-seco-7-phenyl-cholest-4-en-5-carbaldehyd gebildet. Einen analogen B-seco-Aldehyd erhält man neben 7-Methyl-cholesta-4,6-dien-3-on auch aus 7-Methyl-cholest-5-en-3,7-diol. DurchJones-Oxidation von 7-Phenyl-cholest-5-en-3,7-diol oder B-seco-Aldehyd erhält man 3,7-Dioxo-6,7-seco-7-phenylcholest-4-en-6-carbonsäure, die nach Behandlung mit Diazomethan als ihr Methylester isoliert wurde.

     

The Synthesis of the Arene Clusters Ru6C(CO)14(η6-Arene) (Arene = C6H5CHMe2, C6H5C4H9, C6H5C3H7, and C6H5C3H5)

On reaction with Ru₃(CO)₁₂, isopropenylbenzene and 4-phenyl-l-butene undergo hydrogenation, to yield the clusters, Ru₆C(CO)₁₄(⁶-C₆H₅CHMe₂) 1 and Ru₆C(CO)₁₄(⁶-C₆H₅C₄H₉) 2, respectively. With allylbenzene, both hydrogenation and isomerization occurs affording Ru₆C(CO)₁₄(⁶-C₆H₅C₃H₇) 3 and Ru₆C(CO)14(⁶-C₆H₅C₃H₅) 4. The structures of 1 and 2 have been established by single crystal X-ray diffraction. One of the Ru–Ru bond lengths in 2 is unusually long and extended Hückel molecular orbital calculations have been used in an attempt to rationalize this feature.     

Facile Synthesis of 6β-Hydroxy-7α(H)-eudesma-4-en-3-one and β-Cyperone

Eudesmane derivatives have been drawing considerable attention due to their wide spectrum of biological proerties, particulaly antifeedant, cell growth inhibitory and plant growth regulating activities.¹ In recent years a number of C-6 oxyfunctionalized eudesmanes and β-dihydroagarofurans,such as compounds 3-6,have been isolated from nature sources. However the reports on the synthesis of this particular kind of compounds are few and the reported syntheses are generally by synthetic methodology starting from α-santonin 2². Our interest of study on the synthesis of this kind of compounds prompted us to investigate a new synthetic route from cheap material (+)-dihydrocarvone 7.     

Synthesis of new α-chloropyridine derivatives of steroidal 3β,5α,6β-triols and 3β,5-dihydroxy-6-ketones

New steroid derivatives containing 6-chloropyridine groups characteristic of the alkaloid epibatidine and neonicotinoid insecticides were synthesized by reacting 3β,5α,6β-trihydroxysteroids or 3β,5-dihydroxy-6ketosteroids with 2-chloro-5-chloromethylpyridine. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 180-182, March-April, 2009.     

Crystal Structure of 6β,7β,14β-Trihydroxy-1α-acetoxy-7α,20-epoxy-ent-kaur-16-en-15-one

6β,7β,14β-Trihydroxy-1α-acetoxy-7α,20-epoxy-ent-kaur-16-en-15-one was isolated from the natural plant of Isodon japonica (Burm.f), Haravar. galaucocalyx (maxim) Hara. The structure was elucidated by means of spectral and chemical studies. In addition, its crystal was determined by single-crystal X-ray diffraction analysis. It crystallizes in triclinic, space group P1, Z = 2, a = 6.3506(4), b = 13.5766(8), c = 15.2777(9) , α = 80.506(1), β = 83.856(1), γ = 88.307(1)o, C25H36O9, Mr = 480.54, V = 1291.64(13) 3, Z = 2, Dc = 1.236 g/cm3, F(000) = 516, μ = 0.093 mm-1, S = 0.988, the final R = 0.0761 and wR = 0.1955. Flack factor is 0.02(19), and the largest peak and deepest hole on the final difference Fourier map are 0.556 and –0.265 e/3, respectively. The X-ray diffraction shows the existence of intermolecular C–H…O (DA) hydrogen bonds between adjacent molecules.     

Synthesis of ( )-5α-Hydroxy-β-selinene and (-)-5β-Hydroxy-β-selinene

Eudesmanederivativeshavebeendrawingconsiderableattentionduetotheirwidespectrumofbiologicalproperties,particularlyantifeedant,cellgroWthinhibitoryandplantgroWthregulatingactivitiesl'2.Recently,twoepimericeudesmanederivatives( )-5a-hydroxy-6-selinene1and(-)-56-hydroxy-6-selinene2wereisolated3fromtheaerialpartsofCSubtraPicaFMell.,andtheirstructuresweredeterminedbyspectroscopicmethods.Herein,wereportafacilesynthesisofbothtwodiastereomers1and2from( )-dihydrocarvone3infivesteps,usingtheregioselect…     

Heats of formation of C(6)H(5)(•), C(6)H(5)(+), and C(6)H(5)NO by threshold photoelectron photoion coincidence and active thermochemical tables analysis

Threshold photoelectron photoion coincidence has been used to prepare selected internal energy distributions of nitrosobenzene ions [C(6)H(5)NO(+)]. Dissociation to C(6)H(5)(+) + NO products was measured over a range of internal energies and rate constants from 10(3) to 10(7) s(-1) and fitted with the statistical theory of unimolecular decay. A 0 K dissociative photoionization onset energy of 10.607 ± 0.020 eV was derived by using the simplified statistical adiabatic channel model. The thermochemical network of Active Thermochemical Tables (ATcT) was expanded to include phenyl and phenylium, as well as nitrosobenzene. The current ATcT heats of formation of these three species at 0 K (298.15 K) are 350.6 (337.3) ± 0.6, 1148.7 (1136.8) ± 1.0, and 215.6 (198.6) ± 1.5 kJ mol(-1), respectively. The resulting adiabatic ionization energy of phenyl is 8.272 ± 0.010 eV. The new ATcT thermochemistry for phenyl entails a 0 K (298.15 K) C-H bond dissociation enthalpy of benzene of 465.9 (472.1) ± 0.6 kJ mol(-1). Several related thermochemical quantities from ATcT, including the current enthalpies of formation of benzene, monohalobenzenes, and their ions, as well as interim ATcT values for the constituent atoms, are also given.     

A Facile Synthesis of 6β-Hydroxy-7α(H)-eudesma-4-en-3-one

Sesquiterpenesconstituteagroupofnaturalcompoundswhichexhibitconsiderablebiologicalactivities,suchasantiinflamatoryicytyotoxic'andcytotoxic',seedgendnation'andmolluscacidalactivities4.InrecentyearsanumberofC-6oxyfunctionalizedeudesmanesand6-dihydroagarofurans,suchascomPounds3-6',havebeenisolatedfromnaturesources.HoweverthereportSonthesynthesisofthisparticularkindofcompoundsarefewandthereportedsynthesesaregenerallybysyntheticmethodologystartingfroma-santonin2e.Ourinterestofstudyonthesynthesisof…     

Synthesis of (24R)-3β,5,14α-trihydroxy-5α-stigmast-7-en-6-one 3-benzoate

An ecdysteroid analog has been synthesized from -sitosterol.Institute of Bioorganic Chemistry, National Academy of Sciences of Belarus', 220141, Belarus', Minsk, ul. Akad. Kuprevich, 5/2. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 488–491, July–August, 1999.     

Synthesis,structure, electrochemistry,and Mössbauer effect studies of (ring)Fe complexes (ring = Cp,Cp1, and C6H7). Photochemical replacement of benzene in the cyclohexadienyl complex [(η5-C6H7)Fe(η-C6H6)]+

Visible light irradiation of cation [(η⁵-C₆H₇)Fe(η-C₆H₆)]⁺ (1⁺) in acetonitrile results in substitution of the benzene ligand giving the labile acetonitrile derivative [(η⁵-C₆H₇)Fe(MeCN)₃]⁺ (2a⁺). The stable isonitrile and phosphite complexes [(η⁵-C₆H₇)FeL₃]⁺ [L = ^tBuNC (2b⁺), P(OMe)₃ (2c⁺), P(OEt)₃ (2d⁺)] were obtained by reaction of 1 with L in MeCN. The structures of 2cPF₆, [CpFe(η-C₆H₆)]PF₆ (3PF₆), and Cp¹Fe(η-C₆H₆)]PF₆ (4PF₆) were determined by X-ray diffraction.The redox activity of the cyclohexadienyl complexes 1⁺, 2b⁺?2d⁺ has been investigated by electrochemical techniques and compared with that of the related cyclopentadienyl complexes 3⁺ and 4⁺. DFT calculations of the redox potentials and the respective geometrical changes were performed.Variable temperature Mössbauer (ME) spectroscopy has elucidated the relationship between structure and formal oxidation state of the iron atom in these complexes. In the case of 3⁺ an unexpected pair of crystallographic changes has been observed and interpreted in terms of both a second and first order phase transition. The mean-square-amplitude-of-vibration of the metal atom has been compared between the ME and X-ray data. ME measurements in a magnetic field have shown that in 4⁺ the quadrupole splitting is positive as it is in ferrocene.     

Synthesis of Novel 17α-Eethynyl-5-androstene-3β, 7β, 17β-triol (HE3286)Derivatives

以脱氢表雄酮为原料,经羟基乙酰化,羰基亚乙二氧基化,CrO3/3,5-二甲基吡啶氧化,硼氢化钠还原,脱17-位亚乙二氧基,脱3-位乙酰基,用叔丁基二甲基氯硅烷(TBDMSC1)保护3,7-OH,17-位环氧化,17-位开环,脱TBDMSC1保护等十步反应合成了四个新型的17α-乙炔基-5-雄甾烯-3β,7β,17β-三醇(HE3286)衍生物,其结构经1H NMR和MS表征.     

8β-hydroxyeremophil-7(11)-ene-12,8α(4β,6α)-diolide分子的晶体结构

8β-hydroxyeremophil-7(11)-ene-12,8α(4β,6α)-diolide was isolated from the Ligularia intermedia and char- acterized by MS, multi NMR and X-ray single crystal diffraction. Its crystal structure was determined as in a orthorhombic type, with space group P212121 with a=6.8519(5), b=10.7191(8), c=18.5942(14) oA, V =1365.67(18) oA3, Z=4, and the calculated density is 1.354 mg/m3. F(000)=592, μ=0.101 mm-1.     

Synthesis, characterization and standard molar enthalpy of formation of Nd(C7H5O3)2·(C9H6NO)

The complex from reaction of neodymium chloride six-hydrate with salicylic acid and 8-hydroxyquinoline, Nd(C₇H₅O₃)₂·(C₉H₆NO), was synthesized and characterized by IR, elemental analysis, molar conductance, and thermogravimatric analysis. The standard molar enthalpies of solution of [NdCl₃·6H₂O(s)], [2C₇H₆O₃(s)], [C₉H₇NO(s)] and [Nd(C₇H₅O₃)₂·(C₉H₆NO)(s)] in a mixed solvent of anhydrous ethanol, dimethyl formamide (DMF) and perchloric acid were determined by calorimetry at 298.15 K. Based on Hess’ law, a new chemical cycle was designed, and the enthalpy change of the reaction

Separation of 18α(H)-, 18β(H)-oleanane and lupane by comprehensive two-dimensional gas chromatography

18α(H)-, 18β(H)-oleanane and lupane are angiosperm-derived biomarkers that are used as age indicators for the Late Cretaceous onwards when the first proliferation of angiosperms occurred. In addition, the 18α(H)-/18β(H)-oleanane ratio is employed as a thermal maturity parameter of crude oil. However, evidence has shown that accurate quantification of these compounds has been impeded by inadequate chromatographic separation by traditional one-dimensional gas chromatography. In this study, we present the separation of 18α(H)-, 18β(H)-oleanane and lupane with comprehensive two-dimensional gas chromatography (GC×GC). Furthermore, it was observed that 18β(H)-oleanane elutes earlier than 18α(H)-oleanane in second dimension (polarity) which we attribute to steric hindrance effects. Two GC conditions have been developed in order to achieve baseline separation of the triterpenoids of interest in complex mixtures such as sediment extracts and crude oils.     

Special Reactions of α,β-Unsaturated Ketones III [1]. Formation and Structure Elucidation of Dimers of 2-Aryl-methyleneketones: (5E)-5-Benzylidene-9β-phenyl-trans-4a-1,2,3,4,4a,5,6,7,8,9a-decahydroxanthen-4aα-ol and 3β,5β-Bis-(4-methoxyphenyl)-2α,4β,6α-trimethyl-4α-propionyl-cyclohexanone [2]

Summary.  The reaction of 2-benzylidenecyclohexanone and 1-(4-methoxyphenyl)-2-methyl-1-penten-3-one with guanidine did not yield the expected 4-phenylhexahydro-2-quinazolinamine and 4-(p-methoxyphenyl)-dihydro-2-pyrimidinamine, respectively, but nitrogen-free products which turned out as [3+3]- and [4+2]-cycloadducts of two molecules of the applied vinylogous ketone each. According to elemental analyses, mass spectra, and, in particular, NMR analyses (¹H and ¹³CNMR, HH-COSY, gs-HSQC, gs-HMBC, 1D TOCSY, NOESY, and 1D NOE difference spectra), the prepared dimers were identified as racemic (5E)-5-benzylidene-9β-phenyl-trans-4a-1,2,3,4,4a,5,6,7,8,9a-decahydroxanthen-4aα-ol and 3β,5β-bis-(4-methoxyphenyl)-2α,4β,6α-trimethyl-4α- propionylcyclohexanone, respectively. Structure and stereochemistry of the dimers are elucidated, and mechanisms for their formation are proposed. Received April 11, 2001. Accepted (revised) May 18, 2001     

Reaction of 5β,6β-epoxy-16α,17α-cyclohexapregnane with methylmagnesium iodide

On treatment with methylmagnesium iodide, 3β-acetoxy-5β,6β-epoxy-16α,17α-cyclo-hexapregnan-20-one undergoes 3-O-deacetylation along with the opening of the 5β,6β-epoxide ring to form 5α-methyl-6β-hydroxy steroid and the 6α-methyl-6β-hydroxy isomer, the 20-keto group remaining intact.     

Synthesis of 3β,6α-dihydroxy-5α-cholan-23-one

Evidence for the presence of 3β,6α-dihydroxy-5α-chol-9(11)-en-23-one in the aglycone mixture from the starfish Marthasterias glacialis is provided by the synthesis of 3β,6α-dihydroxy-5α-cholan-23-one (19) and its identification in the hydrogenated aglycone mixture. The side-chain is constructed from the 23,24-dinorcholanol (13) by reaction of the 22-tosylate (16) with the acetylide anion, followed by hydration of the resulting 23-yne (17).