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1.
Six crystalline compounds, α-cedrol, β-sitosterol, cryptojaponol sugiol and two new diterpene phenols were isolated from the hexane extractive of wood of Juniperus formosana Hayata. Two new phenolic derivatives of deoxocryptojaponol were established as 7α-methoxydeoxocryptojaponol and 7β-hydroxydeoxocryptojaponol, respectively, by chemical and physical evidence. 相似文献
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3.
On the Reactivity of (−)‐(R)‐Carvone and (−)‐4aα,7α,7aβ‐Nepetalactone: Synthesis of New Heterocycles
Aziz El Mebtoul Mohamed Rouani Malika Chammache Houcine Bouidida Abdelkader Ilidrissi 《Helvetica chimica acta》2011,94(3):433-437
The 1,3‐dipolar cycloaddition of 4‐chlorobenzonitrile oxide to the unsaturated system of (?)‐(R)‐carvone occurred exclusively at C(8) to give a new isoxazoline derivative. This derivative reacts with NH2OH to yield a new heterocycle, observed for the first time. On the other hand, the addition of 4‐chlorobenzonitrile oxide to the unsaturated lactone (?)‐4aα,7α,7aβ‐nepetalactone gave, in a good yield, also a new heterocycle, again obtained for the first time. The terpenoid (?)‐(R)‐carvone and iridoid (?)‐4aα,7α,7aβ‐nepetalactone were isolated from Moroccan species Mentha viridis (L.) and Nepeta tuberosa (L.), respectively. The new heterocycles obtained were identified by combination of chromatographic and spectroscopic methods. 相似文献
4.
Silvana Guilardi Ruggiero Maria Teresa do Prado Gambardella Marcelo Cardoso Branco Antonio Jacinto Demuner Luis Claudio A. Barbosa Dorila Pil‐Veloso 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(7):868-869
The crystal structure of 21α‐fluoro‐7‐norvouacapane‐17β,21α‐lactone, C20H25FO3, a new synthetic derivative of the diterpenoid 6α,7β‐dihydroxyvouacapan‐17β‐oic acid isolated from Pterodon polygalaeflorus Benth fruits, is described. 相似文献
5.
Lophenol, cholest-4α-methyl-7-en-3β-ol (1), obtained from Dracaena cochinchinensis (Lour.) S. C. Chen, was structurally modified. It was acetylated to protect 3β-hydroxyl group, and then oxidised by selenium dioxide in acetic acid to give cholest-4a-methyl-8-en-3β, Ta-diol diacetate (3). This compound 3 is unstable in chloroform solution or when heated and easily converted to a diene compound, cholest-4a-methyl-7,14-dien-3β-ol acetate (4). The structures of 3 and 4 were elucidated by means of IR, ^1H NMR, ^13C NMR and MS, and the absolute configuration of 3 was established by X-ray crystallography. The property of 3 was also discussed in this paper. Both 3 and 4 are new compounds and were reported for the first time. 相似文献
6.
Digitoxigenin ( 3 ) was transformed by a Fusarium spec. to 7β-hydroxydigitoxigenin ( 1 ) 1β, 7β-dihydroxydigitoxigenin ( 4 ) and to the hitherto unknown 7β, 11α-dihydroxydigitoxigenin ( 9 ). 7β-acetoxy-digitoxigenin ( 2 ) was degraded to methyl 3β, 7β-diacetoxy-14-hydroxy-5β, 14β, 17αH-etianate ( 11 ). 相似文献
7.
Justus J. Bürgi Sonia Bertrand Fabrice Marger Daniel Bertrand Jean‐Louis Reymond 《Helvetica chimica acta》2016,99(10):790-804
Here, we investigated whether fluorescence labeled small molecule agonists of the α7 nicotinic acetylcholine receptor (nAChR) might be identified to enhance receptor studies. Enantiomerically pure 3‐amino‐quinuclidines appended with fluorophores at the 3‐amino group were synthesized and tested by electrophysiology on human α7 nAChR in Xenopus oocytes, uncovering (R)‐ 4 and (R)‐ 9 as the first examples of fluorescent α7 nAChR agonists. These molecules elegantly incorporate the fluorescent reporter group as part of the pharmacophore itself and provide a new class of tool compounds for the study of these ligand‐gated ion channels. 相似文献
8.
The bifurcated σ-hole···σ-hole stacking interactions between organosulfur molecules, which are key components of organic optical and electronic materials, were investigated by using a combined method of the Cambridge Structural Database search and quantum chemical calculation. Due to the geometric constraints, the binding energy of one bifurcated σ-hole···σ-hole stacking interaction is in general smaller than the sum of the binding energies of two free monofurcated σ-hole···σ-hole stacking interactions. The bifurcated σ-hole···σ-hole stacking interactions are still of the dispersion-dominated noncovalent interactions. However, in contrast to the linear monofurcated σ-hole···σ-hole stacking interaction, the contribution of the electrostatic energy to the total attractive interaction energy increases significantly and the dispersion component of the total attractive interaction energy decreases significantly for the bifurcated σ-hole···σ-hole stacking interaction. Another important finding of this study is that the low-cost spin-component scaled zeroth-order symmetry-adapted perturbation theory performs perfectly in the study of the bifurcated σ-hole···σ-hole stacking interactions. This work will provide valuable information for the design and synthesis of novel organic optical and electronic materials. 相似文献
9.
The condensation reaction between α-keto-β-aroyl (or acyl) -γ-butyrolactones, 4a-4e and o-phenylenediamine or 2, 3-diaminonaphthalene leads under retrograde aldol condensation involving loss of formaldehyde to formation of 3-substituted-3, 4-dihydro-2 (1H) quinoxalinones or benzo [g] quinoxalinones, 7a-7g , respectively as a new convenient synthesis of this type of heterocyclic systems. The reaction of type 4 compound with 4, 5-diaminopyromidine, 8 , was found to proceed differently. 2-[(4-Amino-5-pyrimidinyl)amine]-4-oxo-3-(hydroxymethyl)-4-phenyl-2-butenoic acid 9 was the only product formed when the reaction between 4a and 8 was run in ethanol. The same reaction in glacial acetic acid proceeds with loss of formaldehyde, to afford 7-phenacylidene-7,8-dihydro-6 (1H)-pteridione 10 . The reaction between type 4 compounds and ethylenediamine or 1, 4-phenylenediamine leads to the formation of the bis-condensation products 13–15 , respectively. 相似文献
10.
Sergey V. Krivovichev Elena V. Kir'yanova Stanislav K. Filatov Peter C. Burns 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(6):629-630
The monoclinic modification of dipotassium dichromate, β‐K2Cr2O7, has been synthesized in the K2Cr2O7–H2O system. The structure consists of K+ cations and Cr2O72? dimers. In contrast with triclinic α‐K2Cr2O7 [Kuz'min, Ilyukhin, Kharitonov & Belov (1969). Krist.Tech. 4 , 441–461], the Cr2O72? groups in β‐K2Cr2O7 have twofold crystallographic symmetry and are parallel to each other. 相似文献
11.
A. Lffler F. Norris W. Taub K. L. Svanholt A. S. Dreiding 《Helvetica chimica acta》1970,53(2):403-417
By heating with iron powder at 120–150° some γ-bromo-α, β-unsaturated carboxylic methyl esters, and, less smothly, the corresponding acids, were lactonized to Δ7alpha;-butenolides with elimination of methyl bromide. The following conversions have thus been made: methyl γ-bromocrotonate ( 1c ) and the corresponding acid ( 1d ) to Δα-butenolide ( 8a ), methyl γ-bromotiglate ( 3c ) and the corresponding acid ( 3d ) to α-methyl-Δα-butenolide ( 8b ), a mixture of methyl trans- and cis-γ-bromosenecioate ( 7c and 7e ) and a mixture of the corresponding acids ( 7d and 7f ) to β-methyl-Δα-butenolide ( 8c ). The procedure did not work with methyl trans-γ-bromo-Δα-pentenoate ( 5c ) nor with its acid ( 5d ). Most of the γ-bromo-α, β-unsaturated carboxylic esters ( 1c, 7c, 7e and 5c ) are available by direct N-bromosuccinimide bromination of the α, β-unsaturated esters 1a, 7a and 5a ; methyl γ-bromotiglate ( 3c ) is obtained from both methyl tiglate ( 3a ) and methyl angelate ( 4a ), but has to be separated from a structural isomer. The γ-bromo-α, β-unsaturated esters are shown by NMR. to have the indicated configurations which are independent of the configuration of the α, β-unsaturated esters used; the bromination always leads to the more stable configuration, usually the one with the bromine-carrying carbon anti to the carboxylic ester group; an exception is methyl γ-bromo-senecioate, for which the two isomers (cis, 7e , and trans, 7d ) have about the same stability. The N-bromosuccinimide bromination of the α,β-unsaturated carboxylic acids 1b , 3b , 4b , 5b and 7b is shown to give results entirely analogous to those with the corresponding esters. In this way γ-bromocrotonic acid ( 1 d ), γ-bromotiglic acid ( 3 d ), trans- and cis-γ-bromosenecioic acid ( 7d and 7f ) as well as trans-γ-bromo-Δα-pentenoic acid ( 5d ) have been prepared. Iron powder seems to catalyze the lactonization by facilitating both the elimination of methyl bromide (or, less smoothly, hydrogen bromide) and the rotation about the double bond. α-Methyl-Δα-butenolide ( 8b ) was converted to 1-benzyl-( 9a ), 1-cyclohexyl-( 9b ), and 1-(4′-picoly1)-3-methyl-Δα-pyrrolin-2-one ( 9 c ) by heating at 180° with benzylamine, cyclohexylamine, and 4-picolylamine. The butenolide 8b showed cytostatic and even cytocidal activity; in preliminary tests, no carcinogenicity was observed. Both 8b and 9c exhibited little toxicity. 相似文献
12.
Irradiation in the n→π* absorption band of the α,β-unsaturated γ,δ-epoxyketone 5 in ethanol at ?65° exclusively afforded the rearranged ene-dione 13 , whereas at + 24° under otherwise unchanged reaction conditions or upon triplet sensitization with Michler's ketone and with acetophenone at + 24° essentially identical mixtures of 13 (major product), 14 , and 15 were obtained. Selective π→π* excitation of 5 at ?78° and + 24° led to similar product patterns. The 9β,10β-epimeric epoxyketone 7 selectively isomerized to 14 and 15 at + 24° and n → π* or π → π* excitation. Neither the epoxyketones 5 and 7 nor the photoproducts 13–15 were photochemically interconverted. In separate photolyses each of the latter gave the double bond isomers 16 , 18 , and 19 , respectively. Cleavage of 13 to the dienone aldehyde 17 competed with the double bond shift ( → 16 ) when photolyzed in alcoholic solvents instead of benzene. The selective transformations 5 → 13 (at ?65° and n → π* excitation) and 7 → 14 + 15 are attributed to stereoelectronic factors facilitating the skeletal rearrangements of the diradicals 53 and 55 , the likely primary photoproducts resulting from epoxide cleavage in the triplet-excited compounds 5 and 7 , via the transition states 54 , 56 , and 57 . The loss of selectivity in product formation from 5 at higher temperature and n → π* excitation or triplet sensitization is explicable in terms of radical dissociation into 58 and 59 increasingly participating at the secondary thermal transformations of 53 . The similar effect of π → π* excitation even at ?78° indicates that some of the π,π* singlet energy may become available as thermal activation energy. It is further suggested that the considerably lesser ring strain in 14 and 15 , as compared with 13 , is responsible that selectivity in product formation from 7 is maintained also at +24° and at π → π* excitation. 相似文献
13.
Bufalin ( 1 ) was transformed to 7β-hydroxybufalin ( 2 ) by an aqueous suspension of the mycelium of Absidia orchidis VUILL. (HAGEM. ). Incubation of resibuforgenin ( 9 ) under the same conditions yielded 12α-hydroxyresibufogenin ( 7 ) and, under changed conditions, another monohydroxylated derivative which possesses most likely the structure of 7β-hydroxyresibufogenin ( 10 ). The corresponding cardenolide 3-O-acetyl-14β, 15β-epoxy-14-anhydro-digitoxigenin ( 17 ) gave both the 7β- and the 12α-monohydroxylated derivatives 18 and 22 and another monohydroxylated product 21 of unknown structure. All microbial transformation products are new. 相似文献
14.
Glen B. Deacon Ewan E. Delbridge Brian W. Skelton Allan H. White 《Angewandte Chemie (International ed. in English)》1998,37(16):2251-2252
A higher degree of coordination saturation is attainable through the unusual coordination mode in the title compound 1 , in which the central pyrazolate groups function both as chelating and as bridging ligands. There is some asymmetry in the bridging, and the N atoms of each μ-η2:η2-pyrazolato ligand are 0.07–0.11 Å closer to one of the two Yb centers. 相似文献
15.
C. C. Lee R. L. Chowdhury A. Pirko R. G. Sutherland 《Journal of organometallic chemistry》1986,310(3):391-400
Di-η5-cyclopentadienyliron complexed dications of 9,10-dihydroanthracene, xanthene, thioxanthene and diphenylmethane derived from ligand exchange reactions but without their prior isolation were oxidized with KMnO4 to give, respectively, the dications of anthraquinone, xanthone, thioxanthone and benzophenone, isolated as their dihexafluorophosphate salts. Cyclopentadienyliron complexes of arenes containing a sulfide function were oxidized by m-chloroperbenzoic acid to the corresponding complexed sulfones, and sulfones prepared in this way include the hexafluorophosphate salt of the η6-p-tolysulfonylbenzene, thioxanthene-10,10-dioxide, 9,9-dimethylthioxanthene-10,10-dioxide or dibenzothiophene-9,9-dioxide-η5-cyclopentadienyliron cation. 相似文献
16.
The reaction of [(η5‐L3)Ru(PPh3)2Cl], where; L3 = C9H7 ( 1 ), C5Me5 (Cp*) ( 2 ) with acetonitrile in the presence of [NH4][PF6] yielded cationic complexes [(η5‐L3)Ru(PPh3)2(CH3CN)][PF6]; L3= C9H7 ([3]PF6) and L3 = C5Me5 ([4]PF6), respectively. Complexes [3]PF6 and [4]PF6 reacts with some polypyridyl ligands viz, 2,3‐bis (α‐pyridyl) pyrazine (bpp), 2,3‐bis (α‐pyridyl) quinoxaline (bpq) yielding the complexes of the formulation [(η5‐L3)Ru(PPh3)(L2)]PF6 where; L3 = C9H7, L2 = bpp, ([5]PF6), L3 = C9H7, L2 = bpq, ([6]PF6); L3 = C5Me5, L2 = bpp, ([7]PF6) and bpq, ([8]PF6), respectively. However reaction of [(η5‐C9H7)Ru(PPh3)2(CH3CN)][PF6] ([3]PF6) with the sterically demanding polypyridyl ligands, viz. 2,4,6‐tris(2‐pyridyl)‐1,3,5‐triazine (tptz) or tetra‐2‐pyridyl‐1,4‐pyrazine (tppz) leads to the formation of unexpected complexes [Ru(PPh3)2(L2)(CH3CN)][PF6]2; L2 = tppz ([9](PF6)2), tptz ([11](PF6)2) and [Ru(PPh3)2(L2)Cl][PF6]; L2 = tppz ([10]PF6), tptz ([12]PF6). The complexes were isolated as their hexafluorophosphate salts. They have been characterized on the basis of micro analytical and spectroscopic data. The crystal structures of the representative complexes were established by X‐ray crystallography. 相似文献
17.
L. C. R. Andrade J. A. Paixo M. J. M. de Almeida E. J. Tavares da Silva M. L. S e Melo F. M. Fernandes Roleira 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(1):o82-o83
The title compound, alternatively called 24‐nor‐5β‐chol‐22‐ene‐3β,7α,12α‐triyl triformate, C26H38O6, has a cis junction between two of the six‐membered rings. All three of the six‐membered rings have chair conformations that are slightly flattened and the five‐membered ring has a 13β,14α‐half‐chair conformation. The 3β, 7α and 12α ring substituents are axial and the 17β group is equatorial. The 3β‐formyloxy group is involved in one weak intermolecular C—H⋯O bond, which links the molecules into dimers in a head‐to‐head fashion. 相似文献
18.
A one‐step transformation of γ‐ and δ‐(spiro)lactones into γ,δ‐ and δ,ε‐unsaturated aldehydes with an excess of formic acid in the vapor phase over a supported manganese catalyst is described for the first time. The scope and limitations of this new reaction are shown with different lactones as substrate, and a mechanistic rationale is proposed. 相似文献
19.
A series of novel γ,γ‐difluorinated Goniothalamin analogues 4a – 4i and 6a – 6i were synthesized. The key steps included the construction of C‐5 stereocenter adjacent to gem‐difluoromethylene group by way of lipase AK catalyzed kinetic resolution, the introduction of aryl group via Stille coupling, and lactonization by 1,5‐oxidative cyclization. These γ,γ‐difluorinated Goniothalamin analogues 4a – 4i and their enantiomers 6a – 6i , together with several corresponding γ‐monofluorinated Goniothalamin analogues were biologically evaluated against four different cancer cell lines. Compound 7h showed a nearly equivalent potency as the parent (R)‐Goniothalamin in the micromolar range. The different fluorine effects between fluoromethylene and gem‐difluoromethylene on antitumor activity were discussed through the analysis of bioassay data. 相似文献
20.
Gold(I) as an Artificial Cyclase: Short Stereodivergent Syntheses of (−)‐Epiglobulol and (−)‐4β,7α‐ and (−)‐4α,7α‐Aromadendranediols
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Dr. Javier Carreras Madeleine Livendahl Dr. Paul R. McGonigal Prof. Antonio M. Echavarren 《Angewandte Chemie (International ed. in English)》2014,53(19):4896-4899
Three natural aromadendrane sesquiterpenes, (?)‐epiglobulol, (?)‐4β,7α‐aromadendranediol, and (?)‐4α,7α‐aromadendranediol, have been synthesized in only seven steps in 12, 15, and 17 % overall yields, respectively, from (E,E)‐farnesol by a stereodivergent gold(I)‐catalyzed cascade reaction which forms the tricyclic aromadendrane core in a single step. These are the shortest total syntheses of these natural compounds. 相似文献