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A novel approach to the tricyclic core of the Stemona alkaloids stemofoline and didehydrostemofoline has been discovered that features an intramolecular (3+2) dipolar cycloaddition of an unactivated carbon-carbon double bond with an azomethine ylide; the azomethine ylide was generated by an unprecedented reaction that occurred during a Swern oxidation of an α-(N-cyanomethyl)-β-hydroxy ester. In separate experiments, the efficacy of introducing the requisite oxygen functionality at C(8) and the 1-butenyl side chain at C(3) was established. 相似文献
3.
The title compound, isolated from leaves, is a new alkyl-3-phthalide characterized by an acylated side chain. It has been identified by spectral analysis as [3-(1-β-D-glucosyloxy)-2-hydroxy]benzoyl 3-(3-phthalidyl)-propyl ester. 相似文献
4.
Loss of side chains from different amino acid residues in a model peptide framework of RGGGXGGGR under electron capture dissociation conditions were systematically investigated, where X represents one of the twenty common amino acid residues. The alpha-carbon radical cations initially formed by N-Calpha cleavage of peptide ions were shown to undergo secondary dissociation through losses of even-electron and/or odd-electron side-chain moieties. Among the twenty common amino acid residues studied, thirteen of them were found to lose their characteristic side chains in terms of odd-electron neutral fragments, and nine of them were found to lose even-electron neutral side chains. Several generalized dissociation pathways were proposed and were evaluated theoretically with truncated leucine-containing models using ab initio calculations at B3-PMP2/6-311++G(3df,2p)//B3LYP/6-31++G(d,p) level. Elimination of odd-electron side chain was associated with the initial abstraction of the hydrogen from the alpha-carbon bearing the side chain by the N-terminal alpha-carbon radical. Subsequent formation of alpha-beta carbon-carbon double bond leads to the elimination of the odd-electron side chain. The energy barrier for this reaction pathway was 89 kJmol-1. This reaction pathway was 111 kJmol-1 more favorable than the previously proposed pathway involving the formation of cyclic lactam. Elimination of even-electron side chain was associated with the initial abstraction of the gamma-hydrogen from the side chain by the N-terminal alpha-carbon radical. Subsequent formation of beta-gamma carbon-carbon double bond leads to the elimination of the even-electron side chain and the migration of the radical center to the alpha-carbon. The energy barrier for this fragmentation reaction was found to be 50 kJmol-1. 相似文献
5.
《Tetrahedron letters》1987,28(46):5677-5680
α-Alkylation of the dianions of β-hydroxy sulfoxides proceeds with high 1, 2-asymmetric induction to give threo-α-alkyl-β-hydroxy sulfoxides. The utility of the present reaction was demonstrated in the asymmetric synthesis of (+)- and (3)-cis-7, 8-epoxy-2-methyloctadecanes (disparlure). 相似文献
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Synthesis and Biodegradation of St-g-poly(MMA-co-VAc) Initiated by Manganic Pyrophosphate 总被引:1,自引:0,他引:1
ZHULin-hui CHENMi-feng JIYan XIAHai-ping DINGMa-tai 《高等学校化学研究》2004,20(2):232-235
Methyl methacrylate (MMA) and vinyl acetate (VAc) were grafted onto corn starch with manganic pyrophosphate { [Mn(H2P2O7)3]^3- } as the initiator and water as the reaction medium, The influences of reaction conditions, including pH value, initiator concentration, monomer concentration and its composition, on percent grafting and grafting efficiency were investigated. The graft copolymer was characterized by means of IR spectroscopy, scanning electron micrograph(SEM) and ^1H NMR spectroscopy. The biodegradation experiment showed that the degradation of corn starch-g-poly(MMA-co-VAc) was mainly from starch. However,after poly VAc in the side chain was transformed into poly vinyl alcohol(PVA), both starch and the grafted side chain could be degraded completely. 相似文献
8.
Hideyuki Itoh Atsushi Kameyama Tadatomi Nishikubo 《Journal of polymer science. Part A, Polymer chemistry》1996,34(2):217-225
New hybrid vinyl monomers with both cationic- and radical-polymerizable vinyl groups were synthesized by the reaction of bis[1(chloromethyl)-2-(vinyloxy)ethyl]terephthalate ( 3 ) with unsaturated carboxylic acids using 1,8-diazabicyclo[5.4.0]-undecene-7 (DBU) as a base. The reaction of 3 with methacrylic acid 4a was carried out using DBU in DMSO at 70°C for 24 h to give an 86% yield of the hybrid vinyl monomer ( 5a ). Polycondensation of 3 with unsaturated dicarboxylic acids was also performed using DBU to give hybrid vinyl oligomers with radical polymerizable C (DOUBLE BOND) C groups (VR) in the main chain and cationic polymerizable vinyl ether moieties (VC) on the side chain. The photopolymerization of these hybrid vinyl compounds proceeded smoothly in bulk using either a cationic photoinitiator such as a sulfonium salt or a radical photoinitiator such as acyl phosphine oxide under UV irradiation. © 1996 John Wiley & Sons, Inc. 相似文献
9.
以2-氰基-6-羟基苯并噻唑为原料,与溴乙醛缩二乙醇缩合制得缩醛后再水解合成中间体6-(2-羰乙基)苯并[d]噻唑-2-甲腈(2);7-苯乙酰氨基-3-氯甲基头孢菌烷酸二苯甲酯依次经碘代和Wittig反应得(Z)-3-[3-(2-氰基苯并[d]噻唑-6-氧)丙-1-烯]-8-羰基-7-(2-苯乙酰氨基)-5-噻-1-氮[4.2.0]辛-2-烯-2-甲酸二苯甲酯(5);5经脱保护、缩合和氧化反应合成了3个新的Bluco类似物,其结构经1H NMR,13C NMR和HR-MS(ESI)表征。 相似文献
10.
V. I. Pavlovsky E. A. Semenishina S. A. Andronati I. G. Filippova Yu. A. Simonov M. Gdaniec J. Lipkowski 《Chemistry of Heterocyclic Compounds》2009,45(11):1379-1387
On interacting 7-bromo-5-(2-chlorophenyl)-3-hydroxy-1,2-dihydro-3H-1,4-benzodiazepin-2-one with methyl, hexyl, dodecyl, and
cetyl tosylates, 1-alkyl-7-bromo-5-(2-chlorophenyl)-1,2,4,5-tetrahydro-3H-1,4-benzodiazepin-2,3-diones, and 1-alkyl-7-bromo-5-(2-chlorophenyl)-3-hydroxy-1,2-dihydro-3H-1,4-benzodiazepin-
2-ones were obtained. Only the dione was formed in the case of hexyl tosylate. On alkylating with methyl tosylate only the
3-hydroxy derivative was formed. It was shown that at pH 14 the 1-cetyl and 1-dodecyl-3-hydroxy derivatives were completely
converted into the corresponding diones. The molecular and crystal structures of the compounds were established by X-ray structural
analysis. 相似文献
11.
Mounir A. A. Mohamed Omyma A. Abd Allah Adnan A. Bekhit Asmaa M. Kadry Ahmed M. M. El-Saghier 《Journal of heterocyclic chemistry》2020,57(6):2365-2378
New series of triazole derivatives coupled with amino acids 1a-h were obtained via multicomponent reaction of 2-hydroxy benzaldehyde or 2-hydroxy acetophenone with thiosemicarbazide and different amino acids. The obtained compounds were reacted with p-toluinesulfonyl chloride 2 to give the corresponding sulfonamides 3a-h . Compound 1b was allowed to react with different aromatic aldehydes or cyclic ketone under alkaline conditions to afford the expected imino compounds 4a-d and 6a-c , respectively. These compounds were allowed to react with ethyl glycolate to yield the expected thiazolidinone derivatives 5a-d or 7a-c , respectively. Structures of the newly synthesized compounds were found to be in accordance with their elemental analyses and spectral data. The obtained compounds exhibited very prominent in vitro and in vivo antihyperglycemic effect at a dose of 40 mg/kg body weight compared to the standard drug gliclazide and control. The antidiabetic effect was investigated using oral glucose tolerance test in normal and non-insulin-dependent diabetes mellitus (NIDDM) in STZ-rat model. Compounds 3a - h , 5b , 5c , 5d , 7a , 7b , and 7c showed significant activity in lowering blood glucose (more than 80%) compared to the NIDDM control. 相似文献
12.
The condensation of 3,3-dimercapto-1-phenyl-2-propen-1-one with o-aminothiophenol and o-aminophenol in hot xylene gave 2-phenacylbenzothiazole ( 3 ) and 2-phenacylbenzoxazole ( 5 ). When the reaction with o-aminophenol was carried out in hot benzene, 2-beuzoylthioacctamidophenol ( 4 ) was obtained, which, heated in hot xylene gave 5. Ethyl benzoylacetale by reaction with o-aminothiophenol gave 3 , whereas by reaction with o-aminophenol gave no heterocyclic compound. However, we were able to isolate 2-benzoylacetamidophenol ( 6 ), ethyl β-phenyl-β-(o-hydroxy)phenyliminopropionate ( 7 ), and 2-[β-(o-hydroxy)anilino] cinnamoylamidophenol ( 8 ). Ir and nmr spectra of synthesized compounds point out the existence of tautomers. 相似文献
13.
Annelation reactions of six-membered rings to 1-hydrazinophthalazine, 1, were investigated. With aroyl-(acyl)pyruvates, 2, the desired system was obtained. It was found that the course of the reaction depends on the reaction condition as well as the substituted pyruvates. Thus, 3-(2-oxo-2-substituted ethyl)-4H-as-triazino-[3,4-a]phthalazin-4-one, 4, was the product when 1 reacted with 2 in alcoholic medium. The side chain tauto-merism of 4 was studied by using ir, 1H-nmr, and ms spectral methods. When 1 hydrochloride instead of 1 was reacted with 2, 3-ethoxycarbonyl-s-triazolo[3,4-a]phthalazine, 6, was the major product. The reaction of 1 with benzoylacetone in ethanol afforded the hydrazalone, 9. By ir, 1H-nmr, and 13C-nmr methods it was shown that in solution it is inolved in an enhydrazine-hydrazone as well as a ring-chain tautomerism. Compound 9 upon the action of PPA underwent dehydrative cyclization to 3-methyl-s-triazolo[3,4-a]phthalazine, 10, and 3-methyl-5-phenyl-1-(l-phthalazinyl)pyrazole, 7. The reaction of 1 with ethyl phenylpropiolate in ethanol was reported by others to give 1-(1-phthalazinyl)-3-phenyl-5-pyrazolone, 8. Upon reinvestigation of this reaction it is shown that the product actually is ethyl β-(1-phthalazinylhydrazono)benzenepropanoate, 11. Attempts to synthesize 8 were unsuccessful by this method. In the reaction of 1 with ethyl benzoylacetate the expected hydralazone 11 was easily formed which upon reaction with PPA yielded the desired species 8. 相似文献
14.
Michele D'Ambrosio Antonio Guerriero Francesco Pietra Ccile Debitus 《Helvetica chimica acta》1996,79(1):51-60
Leucascandrolide A ((+)- 1 ), a doubly O-bridged 18-membered macrolide of a new type, i.e., showing little C1-branching vs. extensive 1,3-dioxygenation and a peculiar side chain, was isolated from a calcareous sponge of a new genus, Leucascandra caveolata BOROJEVIC and KLAUTAU from the Coral Sea. Transesterification of (+)- 1 gave the methyl ester 3 , derived from the side chain, and the 5-hydroxy derivative (+)- 2 , derived from the macrolide portion and with the natural configuration at C(5) (axial). Mosher's MTPA esters 4 and 5 obtained from (+)- 2 showed scattered Δδ = (δ(S) ? δ(R)) data. However, inversion of the configuration at C(5) led, via ketone (+)- 6 , to the less encumbered 5-equatorial hydroxy derivative (+)- 7 , whose MTPA esters 8 and 9 gave consistent Δδ data, allowing the assignment of the absolute configuration of (+)- 7 , and hence of (+)- 1 . The structural novelty of (+)- 1 and its powerful antifungal and cytotoxic activities are likely to renew interest in calcareous sponges, previously limited to scarcely biologically active 2-aminoimidazoles. 相似文献
15.
Gurjar MK Pramanik C Bhattasali D Ramana CV Mohapatra DK 《The Journal of organic chemistry》2007,72(17):6591-6594
Schulzeines B (2) and C (3) were synthesized by a convergent strategy using epimeric tricyclic lactam building blocks, 4 and 5, and the C28 fatty acid side chain 6. Syntheses of tricyclic lactams (4/5) were achieved by Bischler-Napieralski reaction. Sharpless asymmetric dihydroxylation and BINAL-H-mediated asymmetric reduction of an enone was employed to prepare the key fatty acid side chain 6. The spectral as well as analytical data of 2 and 3 were in good agreement with the reported data for the natural products, thus confirming their assigned structures. 相似文献
16.
The carbene complex 5-(2,2-dimethyl-2H-chromene)methoxylmethylene chromium pentacarbonyl will undergo a benzannulation reaction with phenylacetylene, 1-pentyne, 3-hexyne, and trimethylsilylacetylene to give 7-hydroxy-10-methoxy-3H-naphtho[2.1-b]pyrans as the primary product. These compounds are difficult to obtain pure due to their sensitivity to air. If the benzannulation reaction is performed in conjunction with protection of the phenol function at C-7, then good to excellent yields of 7-alkoxy-10-methoxy-3H-naphtho[2.1-b]pyrans are afforded. If the 7-hydroxy products are captured by triflic anhydride, then the resulting aryl triflate can be used to access 3H-naphtho[2.1-b]pyrans bearing C-7 carbon substituents. The 7-hydroxy products can be oxidized to 3H-naphtho[2,1-b]pyran-7,10-diones which are stable. The chromenyl carbene complex reacts with 1,6-bis(triisopropylsilyl)-1,3,5-hexatriyne to give a 2,3-dihydro-2,2-dimethylbenzo[de]chromene, a product type that has not been seen before in the reaction of Fischer carbene complexes with alkynes. A mechanism is proposed for this process that involves alpha,beta-hydride elimination from a chromacyclobutane intermediate. Chromenyl tungsten complexes react with alkynes to give products that result from cyclization without CO insertion. 相似文献
17.
The reaction of several di- and triaryl-substituted 3-aryl-3-hydroxy acids and a 4-aryl-3-hydroxy acid in acetic anhydride in the presence of anhydrous zinc chloride has been investigated. It has been shown that the reaction discovered with 3-(2′-thienyl)-substituted 3-hydroxy acids, namely, their conversion under the above stated conditions into α, β-unsaturated methyl ketones,1,2 occurs also with 3-aryl 3-hydroxy acids but to a smaller degree due to the concurrent cyclization reaction which leads to indene-1-ones. It has been established that the unsaturated methyl-ketones obtained, containing three aromatic substituents at the CC bond, exist in s-cis-(CC, CO)-conformation. It has been found that with the 4-aryl-substituted 3-hydroxy acid almost no unsaturated ketone is obtained, whereas instead the main product is a 2,3-disubstituted 1-naphthol which is acetylated under the conditions of the reaction. Its structure has been proved by its UV, IR and NMR spectra and confirmed by the mass spectrum of the compound. 相似文献
18.
DFT法研究3-羟基丙烯醛的双键旋转异构反应机理 总被引:2,自引:0,他引:2
利用密度泛函理论(DFT)分别在B3LYP/6-31G**和B3LYP/6-311++G**的计算水平上优化了基态3-羟基丙烯醛分子在双键旋转异构反应过程中的平衡态以及过渡态的几何构型,分析了反应过程中键参数的变化,计算了该反应的内禀反应坐标(IRC),发现在重排反应途径上存在一个四元环骨架的中间体.通过振动分析对平衡态和过渡态进行了确认,并得到了零点能.计算结果表明,基态3-羟基丙烯醛分子的双键旋转异构反应经过两步完成,第一步反应位垒稍高,第二步反应位垒较低,存在着发生重排反应的可能性. 相似文献
19.
Silchenko AS Kalinovsky AI Avilov SA Andryjaschenko PV Dmitrenok PS Yurchenko EA Kalinin VI 《Natural product research》2012,26(19):1765-1774
New triterpene glycosides, cucumariosides H? (1), H? (2) and H? (3), have been isolated from the Far Eastern sea cucumber Eupentacta fraudatrix. The structures of 1-3 were elucidated using extensive NMR spectroscopy (1H- and 13C-NMR, DEPT, 1H-1H COSY, 1D TOCSY, H2BC, HMBC, heteronuclear single-quantum coherence, and NOESY) and ESI-MS. Glycosides 1-3 are monosulphated branched pentaosides having rare 3-O-methyl-D-xylose as a terminal monosaccharide. Glycosides 1 and 3 contain holostane aglycones, whereas 2 has a 23,24,25,26,27-pentanorlanostane aglycone with an 18(16)-lactone, which is also uncommon for the sea cucumbers. Glycoside 3 contains a very rare ethoxyl radical at C-25 of the aglycone side chain, and it is most probably an artefact that was formed during long storage of the ethanolic extract. Cytotoxic activities of 1-3 against mouse spleen lymphocytes, haemolytic activity against mouse erythrocytes and Ehrlich carcinoma cells have been studied. The presence of 25-hydroxy group in aglycone moiety significantly decreased the activities. 相似文献
20.
Díaz S González A Bradshaw B Cuesta J Bonjoch J 《The Journal of organic chemistry》2005,70(9):3749-3752
[reaction: see text] The total synthesis of the sesquiterpenoid xylarenal A is reported. This first synthetic entry to an eremophilane terpenoid with an exocyclic vinyl aldehyde unit involves the use of the bicyclic enone (+)-3, which after a gamma-oxidation and alpha'-allylation leads to the formation of the ketone (+)-8. After its acylation, an oxidative cleavage of the allyl side chain followed by alpha-methylenation of the resulting aldehyde gives (+)-xylarenal A (1). The synthesis of (-)-xylarenal A from (-)-3 is also reported. Moreover, the first total synthesis of the trinoreremophilane (+)-1alpha-hydroxyisoondetianone (5) is described. 相似文献