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1.
In this lecture, I would like to present efficient synthetic routes towards the total synthesis of syringolide 1 (2)1,2 and secosyrin 1 (3),1 employing 2,4-disubstituted furan 1 as a common precursor. A modified total synthesis of prehispanolone (6)3 from (S)-(+)-Wieland-Miescher ketone (4) via hispanolone (5) will also be discussed. Our methodology for the synthesis of 3,4-disubstituted-lH-pyrroles4 and for the generation of 3,4-didehydrothiophene5 has also guided us to the successful identification of 1-tert-butoxycarbonyl-3,4-didehydro-1H-pyrrole (7),which is presumably the most strained heterocyclic cumulene ever recorded.  相似文献   

2.
In recent years, the synthesis and pharmacology of pyranoflavanoids have been extensively investigated due to their wide range of pharmacological properties[1-3]. Ponganone Ⅲ[4],a new natural pyranoflavanone isolated from the Pongamia pinnala, was identified as (2S)-3',4'-dimethoxy-6',6"-dimethylpyrano-[2",3":7,8]-flavanone (2) on the basis of spectra data. Its precursor,3,4-dimethoxy-2'-hydroxy-6",6"-dimethylchromeno-[2",3":4',3']-chalcone (1) is also a new natural product[5] isolated from the roots of Lonchocarpus subglaucescent. Their total synthesis have not been reported. Herein, we wish to report the first total synthesis of compounds 1 and 2 in order to confirm the proposed structure and further more to evaluate its biological activities.  相似文献   

3.
Linear 1,7-diarylheptanoids (Ar1-C7-Ar2) are a large group of interesting natural products isolated from plants belonging to Alinia,Curcuma, Zingiber, Alnua,Centridobium and Acer genera used as traditional medicines in some oriental countries1. Pharmacological experiments exhibited that some of them had many physiological actions such as anti-inflammatory, antifungicial, antioxidative,antihepatotoxic activities and so on2. Three natural compounds 13, 24 and 35 (gingerone C) having 1,7-diaryl-4-hepten-3-one skeleton were isolated from the rhizomes of Alpinia offocinarum, the wood of Alnus japonica and the rhizomes of Zingiber officinale respectively. Their structures were elucidated as 1,7-diphenylhept-4-en-3-one(1), 1,7-bis(4-hydroxyphenyl)hept-4-en-3-one(2) and 1-(3-hydroxyl-4-methoxyphenyl)-7-(4-hydroxyphenyl)hept-4-en-3-one(3) by spectral method. Herein, we wish to report facile total synthesis of these three natural compounds. Their synthetic routes were shouwn in scheme.  相似文献   

4.
Some Ligularia species have long used as folk remedies due to their antibiotic, antiphlogistic and antitumor activities.1 Compound 1,2 a novel coniferyl alcohol, was isolated from ligularia duciformis(Compoitae). The geometrical structure of 1,determined by spectroscopic techniques, was corresponded to 4-o-(6,-hydroxy-7'(9')-dehydro-6',7'-dihydrogeranyl)-coniferyl alcohol. But its absolute configuration at C-6,has not yet been determined. Herein, we report the total synthesis of (6'S)-(-)-1 from Geraniol 2 through 9 steps (Scheme 1).  相似文献   

5.
In previous work from our laboratory, we demonstrated that α-carbonyl radical cyclization reactions can serve efficiently as key steps in total synthesis of natural products.1 In this presentation,we report the total synthesis of (-)-α-pinguisene from enone 1 via α-carbonyl radical cyclization.  相似文献   

6.
The synthesis and chemistry of polycyclic cage compounds have attracted considerable attention in recent years.1 The vast majority of the work reported in this area has dealt with caybocyclic cage compounds. On the other hand, the synthesis and chemistry of heterocyclic cage compounds have received less attention. Recently, we have accomplished the synthesis of a series of oxa-cage compounds and performed the chemical transformations of these oxa-cage compounds.2 As part of a program that involves the synthesis,chemistry and applications of heterocyclic cage compounds we report here the synthesis of heterocyclic cage compounds 1-12. We also wish to report the applications of compounds 7-12 on the π-facial selectivities. Studies on the cation-binding properties of compounds 1 and 2 and other oxa-cages are undertaken.  相似文献   

7.
Squalene 1 is recognized as the precursor of sterols and polycyclic triterpenoids that play important roles in numerous life processes1. In view of the fact that the cyclization of hexa-1, 5-diene by γ-irradiation2 and some isoprenoid polyenes by photochemical method3 through radical cation intermediates have been reported and that tris (p-bromophenyl)ammoniumyl hexachloroantimonate (TBPA+SbCl6, 2) could oxidize olfines to the corresponding radical cations that underwent pericyclic reactions4, we thought it might be worthwhile to try the biomimetic cyclization of squalene initiated by radical cations. Previously we5 have reported the cyclization of geraniol and nerol to cis-p-mentha-2,8-dien-l-ol by reaction with 2. Herein, we report the cyclization of 1 initiated by 2 in dry dichloromethane to give 20-R-protosta-5,24-diene 3a and 20-S-protosta-5,24-diene 3b in the ratio of 1:1 with the total yield of 20%(Scheme 1).  相似文献   

8.
In recent years, fused heterocycles have been found to possess many unique properties in synthesis and pharmacology. Especially, 1,2,4-triazolo[3,4-b]-1,3,4-thiadiazoles derivatives have been attracting much attention of chemists and pharmacologists because of their broad-spectrum biological activities such as antibacterial1, hypotensive and CNS depressant2 activities. We have prepared some 3,6-substituted 1,2,4-triazolo[3,4-b]-1,3,4-thiadiazoles and found that these compounds exhibited antimacrobial, insecticidal and promote plant growth.3-5 Cinchophen had been used widely as medicine in clinic,but has been obsolete in recent years due to its by-effect. In order to seek for other uses of cinchophen, as a continuation of our preceeding studies, we used cinchophen as the starting material to synthesize ten new 6-aryl-3-cinchophenyl-l,2,4-triazolo[3,4-b]-l,3,4-thiadiazoles 5a-j. Compound 1 was prepared by the reaction of cinchophen and ethanol in the presence of sulfuric acid. 1 then reacted with hydrazine hydrate in absolute ethanol to give 2 which yielded 3 on treatment with CS2 and KOH. On refluxing of 3 with excess hydrazine hydrate, 4 was obtained. 4 reacted with various substituted benzoic acids in the presence of POCl3 to afifort 5a-j.  相似文献   

9.
The importance of the aliphatic α-organothio aldoxime compound 3 in the preparation of various pesticides is well established. Molecules comprising the α-organothio oxime moiety have been reported to exhibit insecticidal,nematocidal,miticidal activities.[1-2] In the synthesis of the compound 3,the chlorination of the corresponding aliphatic aldoxime 1 is the key step.In conventional methods, the aliphatic aldoxime 1 is chlorinated by chlorine,then the resulting hydroxime acid chloride 2 is treated with sodium alkyl mercaptide to obtain the desired compounds 3[3]. Although free Cl2 is the most common chlorinating agent,it is laborious to determine the accurate amount that has been absorbed,and the high reactivity of Cl2 always leads to side reactions. In connection with an our ongoing research project, we require an efficient and simple method for the synthesis of the compound 3.An improved synthesis process according to the following scheme is reported in this paper.  相似文献   

10.
Under catalysis of montmorillonites, arenes could be cholesterylated by cholesterol (1) via a Friedel-Crafts alkylation.1 When phenols were employed as substrates for that reaction, aryl cholesteryl ethers were obtained instead of aryl cholestenes.2 However, β-naphthol (2a) and α-naphthol (2b) gave obviously different products. We report here the identification of these unexpected products from the reaction of 2 with 1 catalysed by montmorillonite K 10.  相似文献   

11.
The gibberellins (GAs) are a group of naturally-occurring tetracyclic diterpenoid plant growth hormones which are essential to the normal growth and development of plants. Over one hundred different GAs have been identified to date and most of these compounds are present in Nature only in minute quantities. Among the biosynthetic pathways of the gibberellins, the oxidation and subsequent removal of carbon-20 in C20-GAS (e.g. 1 and 2) to form C19-GAs (e.g. 3 and 4) is one of the most important process in which GA 20-oxidases are involved1 (Scheme 1). During the course of our investigation into this process, we needed to have access to C20-GAS such as (2) from a more abundant C19-GA such as GA3 (5). A successful route for such transformation may then be adapted for the synthesis of isotopically-labelled C20-GAS for biological studies.  相似文献   

12.
The monoterpenoid acid 1, which is a component of some traditional medicine such as Gymnocladus chinensis baillon in glycoside form,1 was recently isolated from Artemisia sieberi in Iran in free form.2. Its structure has been established to be (E)-2,6-dimethyl-6-hydroxy-2,7-octadienoic acid (1) by chemical and spectroscopic analysis. Its methyl ester derivative 2,was isolated from the antibacterial extracts of the leaves of Piper aduncum3 as well. Acacialactam, a natural product isolated from the seeds of Acacia concinna DC.(Legunninosae) used in folk medicine of several tropical countries for treating some skin diseases, was assigned structure 4 by Sekine et al4 on the basis of its physical and spectral properties.  相似文献   

13.
An efficient synthesis ofα-D-GlcpNAc-(1→2)-[α-D-ManpNAc-(1→3)-]α-L-Rhap-(1→2)-α-L-Rhap-(1→3)-α-L-Rhap(1), the repeating unit of the O10 antigen from Acinetobacter baumannii was achieved via sequential assembly of the building blocks,p- methoxylphenyl 2,4-di-O-benzoyl-α-L-rhamnopyranoside(2);2-O-allyloxycarbonyl-3,4-di-O-bcnzoyl-α-L-rhamnopyranosyl tri- chloroacetimidate(3);4-methoxylphenyl 3-O-allyloxycarbonyl-4-O-benzoyl-α-L-rhanmopyranoside(4);2-azido-3-O-benzoyl-2- deoxy-4,6-O-isopropylidene-α-D-mannopyranosyl trichloroacetirnidatc(5);2-azido-3,4,6-tri-O-benzoyl-2-deoxy-α,β-D-glucopyr- ano syl trichloroacetimidatc(6).The total yield of 1 from 4 was 4.7%.  相似文献   

14.
(13S)-hydroxyneocembrene(18), a cembranoid which was isolated in 1988 from soft coral Sarcophyton trocheliophorum1, has been shown to be an effective inductor of the release of labeled glucose from the lecithincholesterol liposomes and have cytostatic activities2. The geometrical structure and absolute configuration of 18 have been defined to be 1S, 2E, 7E, 11E, 13S. Herein, we report the total synthesis of (±)-13hydroxyneocembrene(18).  相似文献   

15.
Under acidic conditions, α,α-dimethyl-β,γ-unsaturated cyclohexanones undergoes an enone-benzene rearrangement leading to aromatic derivatives1-4. We recently run an enone-benzene rearrangement of 4,4-dimethyl-cholest-5-en-3-one (1a) catalysed by montmorillonite K-10 to give 1,3,4-trimethyl-19-norcholesta-1,3,5(10)-triene (2a) in moderate yield accompanying intractable mixture of hydrocarbons as by products5. Repetition of this reaction by employing TsOH as a catalyst, 2a was obtained in 65% yield and a new product, 6-methyl-3-isopropyl-A,19-dinorcholesta-6,8,10(5)-triene (3a), was also isolated in 25% yield. The formation of 3a has not been reported in earlier studies1-5. Herein we report the novel enone-benzene rearrangement of 4,4-dialkylcholest-5-en-3-ones (1a~d) leading to ring-B aromatic steroidal hydrocarbons (3a~d) catalysed by TsOH (Scheme 1).  相似文献   

16.
α-Carbonylthioformamide 1 and α-thiocarbonylthioformamide 1 were synthesized by Adiwidjaja in 19801. However, there is no report of these compounds related their properties and reaction activities2. Compound 1 has two possible sites for nucleophilic attack. In our previous works., it was used to synthesize a lot of heterocyclic compounds (Scheme l)3-6.  相似文献   

17.
Hexahydrobenzo[b]furan-3-one(3) and hexahydro-1H-3-indolone (4) are potentially useful intermediates for total synthesis of natural products, such as the hexahydrobenzofuran unit (5) of avermectins and pancracine (6). Anionic cyclization approach toward (3) and (4) have been developed. Their application to the total synthesis of (5) and (6) will be presented.  相似文献   

18.
Betulin (1a) is an abundant natural product in the birch bark. Betulin itself currently has little usage. However, allobetulin (2a) has been used as an important intermediate in the further transformation of triterpenoids and as a sample for biological studies.1 For example, allobetulin was further transformed to a highly active antifeedant for heliothis zea larvae. Some biomarkers (3a,b; 4a,b) with the same or similar structure as ring-E of 2a were identified in a brown coal.3 Consequently, the conversion of 1a to synthetically, biologically and geochemically more important 2a is of great significance. The transformation of 1a to 2a was reported as early as 1922 by Schulze et al in which betulin was isomerized by formic acid, involving formation and hydrolysis of allobetulin formate, to give 2a in moderate yield.4  相似文献   

19.
Metronidazole(MTZ) is an important antibiotic, which has been widely applied to cure protozoal and bacterial diseases for human beings or animals. Herein, three novel drug supramolecular crystals constructed by MTZ with 2,5-dihydroxy-benzoic acid(2,5-DHBA)(1), 2,6-dihydroxy-benzoic acid(2,6-DHBA)(2) and 3,5-dihydroxy-benzoic acid(3,5-DHBA)(3), respectively, have been discovered. The hydrogen bonds of N-H···O(O-H···N), C-H···O and O-H···O play important roles in the 3D supramolecular framework formation for crystals 1-3. Interestingly, due to the vary locations of the substituent groups, the two-dimensional layers in crystals 1 or 2 are constructed via intermolecular hydrogen bonds between MTZ and 2,5-DHBA or 2,6-DHBA, while in crystal 3 water molecules play a significant role except the intermolecular hydrogen bonds between MTZ and 3,5-DHBA. In addition, five synthons of I R22(8), II R33(9) in crystal 1, III R12(4), IV R22(8) in crystal 2 and V R22(7) in crystal 3 formed through various hydrogen bonds are founded in this work. Systematic studies of syntheses, crystal structures and thermal analysis are reported.  相似文献   

20.
Aluminescent Ag-based metal-organic framework(1) has been synthesized and its structure has been characterized. Compound 1 was fabricated using the Ag+ and bbimb2‒ ligands and manifestes a rare LON topology. Compound 1 is selective not only in detecting traces of Fe3+ and 2,4,6-trinitrophenol(TNP) via luminescence quenching, but also demonstrates high selectivity in the presence of other competitors. Compound 1’s Ksv values towards Fe3+ can reach as high as 9.3×103 L/mol, which is higher than those of several other MOF materials. It is also a recyclable luminous sensor with the potential to be utilized for detecting TNP. Hence, based on its characteristics, compound 1 can be regarded as a prospective luminescence sensor for detecting Fe3+ and TNP.  相似文献   

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