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1.
Joseph G. Lombardino 《Journal of heterocyclic chemistry》1973,10(5):697-698
Several 2-aryl-4-phenyl-5-trifluoromethylimidazoles have been made from the previously unknown 1-phenyl-3,3,3-trifluoro-1,2-propanedione monohdyrate. One analog, 4-phenyl-2,5-bis(trifluoromethyl)imidazole, is quite acidic, exhibiting pKa 8.1. 相似文献
2.
K. V. Shcherbakov Ya. V. Burgart V. I. Saloutin 《Russian Journal of Organic Chemistry》2013,49(5):719-729
Ethyl 5,6,7,8-tetrafluoro-4-oxo-2-phenyl-4H-chromene-3-carboxylate in reactions with primary amines is characterized by a chromone-coumarin rearrangement affording 3-[amino(phenyl)methylene]-6,7,8-trifluoro-2H-chromene-2,4(3H)-diones, and ethyl 4-oxo-2-phenyl-5,6,7,8-tetrafluoro-4H-chromene-3-carboxylate characteristically adds the amine at the C2 site of the flavone furnishing 3-amino-3-phenyl-2-(2,3,4,5-tetrafluoro-6-hydroxybenzoyl)acrylates which depending on the substituent at the amino group are capable of intramolecular cyclization into 3-[(alkylamino)(phenyl)methylene]-5,6,7,8-tetrafluoro-2H-chromene-2,4(3H)-dione or in the case of benzylamine substituent, into ethyl 1-benzyl-5-hydroxy-4-oxo-2-phenyl-6,7,8-trifluoro-1,4-dihydroquinoline-3-carboxylate. The main process in the reaction of tri- and tetrafluoroflavones with secondary amine (1-methylpiperazine) is the nucleophilic substitution at the C7 of flavone. In the reaction with 1,2-phenylenediamine 3-[(2-aminophenyl)amino]-3-phenyl-2-(2,3,4,5-tetrafluoro-6-hydroxybenzoyl)acrylate was obtained from tetrafluoroflavone and 1H-benzimidazol-2-yl(3,4,5-trifluoro-2-hydroxyphenyl)methanone, from trifluoroflavone. 相似文献
3.
Nicholas M Shaw 《Tetrahedron》2004,60(3):747-752
The substrate specificity of the heat-stable stereospecific amidase from Klebsiella oxytoca was investigated. In addition to the original substrate, 3,3,3-trifluoro-2-hydroxy-2-methylpropanamide, the amidase accepted 2-hydroxy-2-(trifluoromethyl)-butanamide and 3,3,3-trifluoro-2-amino-2-methylpropanamide as substrates. Compounds with larger side chains and compounds where the hydroxyl group was substituted with a methoxy group, or in which the CF3 group was substituted by CCl3, were not accepted. The biotransformation is a new synthetic route to (R)-(+)-3,3,3-trifluoro-2-amino-2-methylpropanoic acid, and its related (S)-(−)-amide, and to (R)-(+)-2-hydroxy-2-(trifluoromethyl)-butanoic acid and its related (S)-(−)-amide. 相似文献
4.
2,2,2-Trifluorodiazoethane reacts with trifluoroacetonitrile in the dark at room temperature to give a 2-(2,2,2-trifluoroethyl)-4, 5-bis(trifluoromethyl)triazole, the 1,2,3-triazole structure being preferred to the 1,2,4-isomer on the basis of the 19F n.m.r. spectrum. The diazoethane reacts more slowly with trichloroacetonitrile, again forming the N-alkylated triazole even in the presence of an excess of the nitrile. No identifiable adduct resulted with acetonitrile. Hexafluoroisopropyl-ideneimine is first N-alkylated and then undergoes addition to form 1-(2,2,2-trifluoro-1-trifluoromethyl)ethyl-4,5-bis(trifluoromethyl)-?-1,2,3-triazoline, but N-methylhexafluoroisopropylideneimine failed to react. Trifluoroacetaldehyde and trichloroacetaldehyde give mixtures of the ketone (formed by insertion of the CF3CH group into the aldehyde CH bond) and the - and -oxirans, apparently a β-hydroxydiazoalkane. 相似文献
5.
Yu. Yu. Kotorova A. T. Gubaidullin V. F. Mironov L. M. Burnaeva A. B. Dobrynin R. Z. Musin I. A. Litvinov I. V. Konovalova 《Russian Journal of General Chemistry》2006,76(3):437-446
The reaction of hexafluoroacetone with 2-alkoxy-6(7)-chloro-1,3,2-benzodioxaphosphorin-4-ones yielded 7-and 8-chloro-substituted 2-alkoxy-2,5-dioxo-4,4-bis(trifluoromethyl)-1,3,2λ5-benzodioxaphosphepines. Their steric structure was studied by single-crystal X-ray diffraction. The effect of fluorinated substituents on the crystal packing of the benzophosphepines was demonstrated. Hydrolysis of these compounds gave the corresponding 4-and 5-chloro-substituted 2-(2-hydroxyphenyl)-2-oxo-1,1-bis(trifluoromethyl)-ethanols; the structure of 2-(2-hydroxy-5-chlorophenyl)-2-oxo-1,1-bis(trifluoromethyl)ethanol was also proved by single-crystal X-ray diffraction. 相似文献
6.
T. I. Filyakova L. V. Saloutina A. Ya. Zapevalov P. A. Slepukhin M. I. Kodess V. I. Saloutin 《Russian Journal of Organic Chemistry》2011,47(5):650-658
2,3-Epoxyperfluoro-2-methylpentane reacts with thiourea in protic (methanol, 2-propanol) and aprotic (dioxane) solvents, and
also with urea in acetonitrile affording unexpected products: 1-(2,2,3,3,3-pentafluoropropionyl)-2-(2,2,2-trifluoro-1-trifluoro-methylethyl)isothiourea,
and 1-(2,2,3,3,3-pentafluoropropionyl)-3-(2,2,2-trifluoro-1-trifluoro-methylethyl)urea respectively that result from the rearrangement
of the intermediately formed ketone in the process of the intramolecular “haloform” cleavage. At the same time in dioxane
the 2,3-epoxyperfluoro-2-methylpentane reacts with urea with the formation of a heterocyclic compound, 2-amino-4-pentafluoroethyl-5,5-bis(trifluoromethyl)-4,5-dihydrooxazol-4-ol.
From 1-(2,2,3,3,3-pentafluoropropionyl)-2-(2,2,2-trifluoro-1-trifluoromethylethyl)isothiourea and Cu(OAc)2 a stable fluorine-containing chelate complex was obtained. 相似文献
7.
A series of novel N-benzylcarboxamide derivatives of bicyclic compounds, 3,4-dihydropyrido[3,2-f][1,4]oxazepin-5(2H)-one and 2,3,4,5-tetrahydro-6H-pyrido[2,3-b][1,5]oxazocin-6-one, were synthesized by cyclization of N-benzyl-2-chloro-N-(2-hydroxyethyl)- [and -(3-hydroxypropyl)-] nicotinamides, respectively. Atropisomerism was observed in 5-[3,5-bis(trifluoromethyl)benzyl]-7-phenyl-2,3,4,5-tetrahydro-6H-pyrido[2,3-b][1,5]oxazocin-6-ones due to steric hindrance of the carboxamide moiety and restriction of its rotation. Cyclization of N-[3,5-bis(trifluoromethyl)benzyl]-2-chloro-N-[(2S)-3-hydroxy-2-methylpropyl]-5-methyl-4-phenylnicotinamide gave (3S)-5-[3,5-bis(trifluoromethyl)benzyl]-3,8-dimethyl-7-phenyl-2,3,4,5-tetrahydro-6H-pyrido[2,3b][1,5]oxazocin-6-one, which exists predominantly in the thermodynamically stable aR-conformer in CDCl3. This compound showed excellent NK1-antagonistic activity with IC50 value (in vitro inhibition of [125I]-Bolton-Hunter-substance P binding in human IM-9 cells) of 0.47 nM, which is ca. 200-fold more potent than that of its enantiomer, indicating that the atropisomer chirality affects NK1-receptor recognition. 相似文献
8.
Ralph-Matthias Schoth Dmitrii Sevenard Kazimir Pashkevich Gerd-Volker Rschenthaler 《Coordination chemistry reviews》2000,210(1):101-134
The role of fluorinated β-diketones, their tautomers (keto–enols) and their derivatives as reagents towards λ3P compounds is reviewed, including 2-trifluoroacetyl phenols, possessing formally a keto–enol system, and their derivatives. In an ‘insertion’ reaction phosphine and the keto–enol tautomers of 1,1,1,5,5,5-hexafluoro- and 1,1,1-trifluoropentan-2,4-dione furnished primary (S) or (R) α-hydroxy phosphines, whose enol functions probably isomerized the corresponding keto compounds. Further addition and isomerisation furnished 1,3α,5,7β-tetrakis(trifluoromethyl)-2-phospha-6-oxa-9-oxabicyclo[3.3.1]-nonan-3β,7α-diol and 1,7-trifluoromethyl-3,5-methyl-2,4,8-trioxa-6-phophaadamantane, exclusively one diastereomer in each case. The main mechanistic feature of these reactions is a consecutive diastereoselective hemiketal cyclization. 1,1,1,5,5,5-Hexafluoro- and 1,1,1-trifluoropentan-2,4-dione, as well as 2-trifluoroacetyl phenol and its imino derivatives reacted diastereospecifically with phosphonous acid dichlorides, RPCl2 to give in a concerted mechanism thermally stable tricyclic λ5σ5P phosphoranes containing two five-membered rings and one six-membered ring. Surprisingly, the two CF3 groups bonded to an sp3-hybridized carbon were in a cisoid arrangement having closest non-bonding FF distances of 301.4 or 273.5 pm. These findings reflect the ‘through space’ F---F coupling constants of the tricyclic phosphoranes (JFF=4.0–7.0 Hz), in solution. 4,4,4-Trifluoro-3-hydroxy-1-phenyl-butan-1-one and methyl or phenyl phosphonous acid dichlorides gave similar tricyclic phosphoranes decomposing at ambient temperature to furnish 1,2λ5σ4-oxaphospholanes and (E)-1,1,1-trifluoro-4-phenyl-but-2-en-4-one. Dialkylphosphites and 1,1,1,5,5,5-hexafluoropentan-2,4-dione reacted to give either the (Z)-enol phosphonates or the respective γ-ketophosphonates from which in two cases four diastereomeric 2-oxo-2,5-dialkoxy-3,5-bis(trifluoromethyl)-3-hydroxy-1,2λ5σ4-oxa-phospholanes were obtained. 2-Trifluoroacetyl cyclohexanone, 4,4,4-trifluoro-3-trimethylsiloxy-1-phenylbutan-1-one, 1-benzoyl-2-trifluormethyloxirane, 1-benzoyl-2-trifluoro-methylaziridine, 2-trifluoroacetyl-1-trimethylsiloxybenzene and (trifluoroacetyl-1-phenyl) diethyl phosphate reacted with tris(trimethylsilyl) phosphite to give functionalized α-trimethylsiloxy phosphonates, which could easily be transferred into the respective phosphonic acids. In the case of an oxirane and an aziridine ketone no ring cleavage was observed. For 1,1′-(2-hydroxy-5-methyl-m-phenylene)-bis-ethanone and 1,1′-(2-trimethylsiloxy-5-methyl-m-phenylene)-bis-ethanone benzoxaphospholanes were obtained. Trialkyl phosphites and 1,1,1,5,5,5-hexafluoropentan-2,4-dione furnished cyclic phosphoranes containing the 3-hydroxy-3,5-bis(trifluoromethyl)-1,2λ5σ5-oxaphospholene structural element, stable at ambient temperature only in the case of one cyclic phosphite precursor. (E)-1,1,1-Trifluoro-4-phenyl-but-2-en-4-one and trimethylphosphite reacted to form 1,2λ5σ5-oxaphosphol-4-ene as the sole product. Results similar to the reaction of 1,1′-(2-hydroxy-5-methyl-m-phenylene)-bis-ethanone with diethyltrimethylsilylphosphite were obtained for trimethylphosphite and 2-trifluoroacetyl phenol where a deoxygenated phosphorane was found, easily hydrolyzed to give the respective phosphonic acid. With dialkylisocyanato phosphites and the keto components, 1,1,1,5,5,5-hexafluoro- and 1,1,1-trifluoropentan-2,4-dione, 4,4,4-trifluoro-1-phenyl-1,3-butandione, 2-trifluoroacetyl cyclohexanone, 2-trifluoroacetyl phenol and 1,1′-(2-hydroxy-5-methyl-m-phenylene)-bis-ethanone reacted in a ‘double’ cycloaddition to form bicyclic phosphoranes containing the 4,8-dioxa-2-aza-1λ5σ5-phosphabicyclo[3.3.0]-oct-6-en-3-one ring system; for the imino derivatives of 2-trifluoroacetyl phenol a corresponding 8-oxa-2,4-diaza- system was generated. For (E)-1,1,1,5,5,5-hexafluoro-4-trimethylsiloxy-3-penten-2-one however, a cyclic spiroimino phosphorane was obtained which underwent a [2+2] cyclodimerization to form a diazadiphosphetidine. Dimethylpropynyl phosphonite and 1,1,1,5,5,5-hexafluoropentan-2,4-dione yielded diastereoselectively a bisphosphorane, namely 1,4-bis(trifluoromethyl)-3,6-dioxa-2,2,7,7-tetramethoxy-2,7-di(1-propynyl)-2,7-diphosphabicyclo[2.2.1] heptane. When trimethylsilanyl–phosphenimidous acid bis-trimethylsilanyl–amide, Me3SiN=PN(SiMe3)2, was allowed to react with 1,1,1,5,5,5-hexafluoro- and 1,1,1-trifluoropentan-2,4-dione, (E)-1,1,1,5,5,5-hexafluoro-4-trimethylsiloxy-3-penten-2-one, 2-trifluoroacetyl cyclopentanone, 2-trifluoroacetyl phenol and its imino derivatives, 2-imino-1,2λ5σ4-oxaphospholenes were found containing two diastereomers in each case, which added hexafluoroacetone across the P=N bond to give 1,3,2λ5σ5-oxazaphosphetanes. 相似文献
9.
Chiral Building Blocks for Syntheses by Kolbe Electrolysis of Enantiomerically Pure β-Hydroxybutyric-Acid Derivatives. (R)- and (S)-Methyl-, and (R)-Trifluoromethyl-γ-butyrolactones, and -δ-valerolactones The coupling of chiral, non-racemic R* groups by Kolbe electrolysis of carboxylic acids R*COOH is used to prepare compounds with a 1.4- and 1.5-distance of the functional groups. The suitably protected β-hydroxycarboxylic acids (R)- or (S)-3-hydroxybutyric acid, (R)-4,4,4-trifluoro-3-hydroxybutyric acid (as acetates; see 1 – 6 ), and (S)-malic acid (as (2S,5S)-2-(tert-butyl)-5-oxo-1,3-dioxolan-4-acetic acid; see 7 ) are decarboxylatively dimerized or ‘codimerized’ with 2-methylpropanoic acid, with 4-(formylamino)butyric acid, and with monomethyl malonate and succinate. The products formed are derivatives of (R,R)-1,1,1,6,6,6-hexafluoro-2,5-hexanediol (see 8 ), of (R)-5,5,5-trifluoro-4-hydroxypentanoic acid (see 9,10 ), of (R)- and (S)-5-hydroxyhexanoic acid (see 11 ) and its trifluoro analogue (see 12, 13 ), of (S)-2-hydroxy- and (S,S)-2,5-dihydroxyadipic acid (see 23, 20 ), of (S)-2-hydroxy-4-methylpentanoic acid (‘OH-leucine’, see 21 ), and of (S)-2-hydroxy-6-aminohexanoic acid (‘OH-lysine’, see 22 ). Some of these products are further converted to CH3- or CF3-substituted γ- and δ-lactones of (R)- or (S)-configuration ( 14 , 16 – 19 ), or to an enantiomerically pure derivative of (R)-1-hydroxy-2-oxocyclopentane-1-carboxylic acid (see 24 ). Possible uses of these new chiral building blocks for the synthesis of natural products and their CF3 analogues (brefeldin, sulcatol, zearalenone) are discussed. The olfactory properties of (R)- and (S)-δ-caprolactone ( 18 ) are compared with those of (R)-6,6,6-trifluoro-δ-caprolactone ( 19 ). 相似文献
10.
(?)-(R)-4,4,4,4′,4′,4′-Hexafluorovaline hydrochloride ((R)- 5 ) of 98% ee is prepared from β,β-bis(trifluoromethyl)acrylic acid (= benzyl 4,4,4-trifluoro-3-(trifluoromethyl)but-2-enoate; 1 ) in 4 steps with an overall yield of 9.6%. Key step is the separation of the TsOH salts of the diastereoisomers obtained by anti-Michael addition of (+)-(R)-1-phenylethylamine ( 2 ) to 1 (→ (R,R)- 3 ). In contrast to the published (S)-chirality, the X-ray structure analysis of (R,S)- 6 reveals, that (R)-chirality has to be assigned to the levorotatory (?)-4,4,4,4′,4′,4′-hexafluorovaline hydrochloride. 相似文献
11.
Thermally Stable Trialkyl-2,2,2-trifluoro-1-(trifluoromethyl)-ethoxyphosphonium Iodides The phosphinites R1R2POCH(CF3)2 (R1 = R2 = Me, tBu; R1 = Me, R2 = tBu) react with methyl iodide to give the thermally very stable phosphonium iodides [R1R2MePOCH(CF3)2]+I?. In the case of tBu2POCH(CF3)2 a sublimable 1:1 adduct is formed with boron trichloride. 相似文献
12.
rel-(2R,3R)-N-Benzoylamino-6,7-bis(methoxycarbonyl)-2,3-dihydro-1-oxo-1H,5H-pyrazolot[1,2-a]-pyrazoles 5 , accesible by cycloaddition of dimethyl acetylenedicarboxylate ( 3 ) to (1Z)-rel-(4R,5R)-1-aryl-methylidene-4-benzoylamino-5-phenyl-3-pyrazolidinone-1-azomethine imines 4 , undergo oxidative ring cleavage with methanolic bromine giving rel-(2R,3R)-N-benzoyl-3-phenyl-3-[5-aryl-3,4-bis(methoxy-carbonyl)pyrazolyl-1]alanine methyl esters 6 as products. 相似文献
13.
Reaction of dialkyl (2S,3S)- or (2S,3R)-tetrahydro-3-hydroxy-5-oxo-2,3-furandicarboxylates with POCl3 in pyridine followed by diazomethane resulted in the isolation of dialkyl 2S-4-methoxy-5-oxo-2,5-dihydro-2,3-furandicarboxylates, which are analogues of the Quararibea metabolite chiral enolic-γ-lactone (3-hydroxy-4,5-(R)-dimethyl-2(5H)-furanone). An unusual α-hydroxylation of γ-butyrolactone takes place involving POCl3 in pyridine. When the dehydration was facilitated with methanesulfonyl chloride in triethylamine, instead of POCl3, aromatic dialkyl 5-[(methylsulfonyl)oxy]-2,3-furandicarboxylates were obtained. 相似文献
14.
Wojciech Nitek Ewa Szymańska Waldemar Tejchman Ewa Żesławska 《Acta Crystallographica. Section C, Structural Chemistry》2023,79(9):334-343
5-Arylidene derivatives of rhodanine show various biological activities. The new crystal structures of five derivatives investigated towards ABCB1 efflux pump modulation are reported, namely, 2-[5-([1,1′-biphenyl]-4-ylmethylidene]-4-oxo-2-thioxothiazolidin-3-yl)acetic acid dimethyl sulfoxide monosolvate, C18H13NO3S2·C2H6OS ( 1 ), 4-[5-([1,1′-biphenyl]-4-ylmethylidene]-4-oxo-2-thioxothiazolidin-3-yl)butanoic acid, C20H17NO3S2 ( 2 ), 5-[4-(benzyloxy)benzylidene]-2-thioxothiazolidin-4-one, C17H13NO2S2 ( 3 ), 4-{5-[4-(benzyloxy)benzylidene]-4-oxo-2-thioxothiazolidin-3-yl}butanoic acid, C21H19NO4S2 ( 4 ), and 5-[4-(diphenylamino)benzylidene]-2-thioxothiazolidin-4-one, C22H16N2OS2 ( 5 ). Compounds 1 and 3 – 5 crystallize in the triclinic space group P, while 2 crystallizes in the monoclinic space group P21/n, where the biphenyl moiety is observed in two positions (A and B). Two molecules are present in the asymmetric unit of 5 and, for the other four compounds, there is only one molecule; moreover, 1 crystallizes with one dimethyl sulfoxide molecule. The packing of the molecules containing a carboxyl group ( 1 , 2 and 4 ) is determined by O—H…O hydrogen bonds, while in the other two compounds ( 3 and 5 ), the packing is determined by N—H…O hydrogen bonds. Additionally, induced-fit docking studies have been performed for the active compounds to investigate their putative binding mode inside the human glycoprotein P (P-gp) binding pocket. 相似文献
15.
Mara E. F. Braibante Gunter Clar Marcos A. P. Martins 《Journal of heterocyclic chemistry》1993,30(4):1159-1160
1-Methyl-5-(trifluoromethyl)-1H-pyrazoles 2, 3 and 4,5-dihydro-1-phenyl-5-(trifluoromethyl)-1H-pyrazol-5-ol 4 were prepared by reaction of 4-alkoxy-1,1,1-trifluoro-3-alken-2-ones 1 and hydrazine, methylhydrazine, and phenylhydrazine, respectively, in good yields. Compound 1 proved to be a versatile building block for the regiospecific construction of pyrazole rings having an 5-trifluoromethyl substituent. 相似文献
16.
《合成通讯》2013,43(19):2987-2995
TiCl4 mediated coupling of alkyl vinyl ketones with α-keto esters and aldehydes provides respectively 2-aryl-2-hydroxy-3-methylene-4-oxoalkanoates and (Z)-keto allyl chlorides in 1 h time at room temperature. Similar coupling of trifluoromethyl phenyl ketone with methyl vinyl ketone produces 1,1,1-trifluoro-2-hydroxy-2-phenyl-3-methylenepentan-4-one. 相似文献
17.
B. A. Shainyan M. V. Ustinov V. K. Bel'skii L. O. Nindakova 《Russian Journal of Organic Chemistry》2002,38(1):104-110
Chiral diamines having a C
2 symmetry, (4S,5S)-2,2-dimethyl-4,5-bis(aminomethyl)-1,3-dioxolane and (5S,5'S)-2,2,2',2'-tetramethyl-3,3'-diphenyl-5,5'-bioxazolidine, were synthesized on the basis of (+)-(2R,3R)-tartaric acid. Their structure was proved by X-ray analysis. The products were used as ligands in rhodium catalyst for enantioselective hydrogenation of -acetamidocinnamic and itaconic acids. 相似文献
18.
《Tetrahedron: Asymmetry》2005,16(16):2748-2753
Using a recombinant E. coli strain overexpressing yeast reductase Ara1p, we reduced racemic 3-oxo-4-phenyl-β-lactam to cis-(3S,4R)-3-hydroxy-4-phenyl-β-lactam as a single enantiopure product. The dynamic kinetic resolution occurred over the course of fermentation at pH 7. Under the same conditions, 3-oxo-4-(2-thiophenyl)-β-lactam 4 and 3-oxo-4-(2-furyl)-β-lactam 5 were not resolved. 相似文献
19.
Masahiro Yoshimura 《Tetrahedron》2007,63(46):11399-11409
Hydrogenation of (Z)-3-phenyl-2-butenoic acid with a Ru(CH3COO)2[(R)-binap] (BINAP=2,2′-bis(diphenylphosphino)-1,1′-binaphthyl) catalyst in methanol gives (S)-3-phenyl-2-butanoic acid and its R enantiomer in a 97:3 (4 atm) to 94:6 (100 atm) ratio in quantitative yield. Both hydrogen gas and protic methanol participate in the saturation of the olefinic bond. Analysis of the products obtained using (Z)-3-phenyl-2-butenoic acid-3-13C and either H2, a 1:1 H2-D2 mixture, or D2 in CH3OD indicates that several catalytic cycles are operative, showing different reactivity and stereoselectivity. The major S enantiomer was formed primarily by the standard Ru monohydride mechanism, whereas the minor R isomer is produced via more complicated routes. 相似文献
20.
《Mendeleev Communications》2023,33(2):194-196
Methyl 4-trifluoro-2-isopropyl-4-oxobutanoate prepared by the improved procedure was cyclized with hydrazines to afford the title pyrazole derivatives. N- and O-alkylation of 4-isopropyl-1-phenyl-3-(trifluoromethyl)pyrazol-5-ol gave trifluoromethyl analogues of Propyphenazone and 5-alkoxy derivatives. 4-Isopropylpyrazoles containing O-butoxy moiety with a terminal trifluoromethyl or acyloxy group were found to demonstrate a promising analgesic activity. 相似文献