共查询到20条相似文献,搜索用时 15 毫秒
1.
Hashem Sharghi Alireza Hassani Nejad 《Phosphorus, sulfur, and silicon and the related elements》2013,188(11):2297-2305
A convenient and efficient procedure for the cleavage of the oxirane rings with ammonium thiocyanate in the presence of phosphorus(V)tetraphenylporphyrin is described. The ring-opening of 1,2- epoxyethanes is found to proceed regioselectively under mild reaction conditions. Thus, several 2-hydroxyethyl thiocyanates, useful intermediates toward biologically active molecules, are easily obtained in very good yields. 相似文献
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Patrick Shelton Toby J. Ligon Jennifer M. Dell Loagan Yarbrough James R. Vyvyan 《Tetrahedron letters》2017,58(35):3478-3481
Cananodine is a guaipyridine alkaloid with activity against liver cancer. Cananodine was synthesized using a remarkable intramolecular opening of a trisubstituted epoxide as the key step in construction of the seven-membered carbocycle of the target. The epoxide opening strategy allows all four stereoisomers of cananodine to be prepared. 相似文献
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The reaction of hemiketals (1–6) with sodium hydroxide and methyl iodide in the presence of TBAI as a catalyst furnished methoxy hemiketals (7–10) in more than 90% yield. 相似文献
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A stereoselective synthesis of pentacyclic steroids has been achieved. Starting from commercially available cholic acid 1, followed by asymmetric epoxidation and by stereoselective epoxide ring opening, employing nucleophilic species, the corresponding products were afforded in good yields. The compounds were being evaluated for their biological activity. 相似文献
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Nasser Iranpoor Habib Firouzabadi Abbas Ali Jafari 《Phosphorus, sulfur, and silicon and the related elements》2013,188(8):1809-1814
The use of thiourea/silica gel provides a green protocol for the easy and high-yielding preparation of thiiranes from different classes of epoxides in the absence of solvent at room temperature. The high stereospecific conversion of (R)(+)-styrene oxide to (S)(+)-styrene sulfide is also reported using this reagent system. 相似文献
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This paper deals with the synthesis of an interpenetrating network made of dimethacrylate and dicycloepoxide oligomers by photopolymerization. More particularly, the influence of several parameters (among which the photoinitiator nature and the reaction temperature) on the polymerization kinetics of each oligomer was studied. Two complementary analysis techniques were then used : the photocalorimetry and the RTIR spectroscopy. The study proceeded in several steps. Firstly, photopolymerization of each monomer was studied. Then, the same study was carried out on mixture of both monomers under conditions in such way than only one network is formed. It was shown that the second compound played the role of plasticizer on the network formed by the first monomer. Finally, the dimethacrylate/dicycloepoxide mixture was studied in the presence of both radical and cationic photoinitiators to synthesize an interpenetrating network (IPN). At 30 °C, ultimate products show a very incomplete epoxide conversion whereas the yield in methacrylic double bonds reaches 70%. On the other hand, epoxy functions react a little more than methacrylic double bonds at 90 °C. It was also shown that the presence of a radical photoinitiator is not necessary, and even slightly unfavourable, since the cationic photoinitiator is able to initiate both radical and cationic polymerization mechanisms. 相似文献
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Olivine-type Co2SiO4 ultrafine particles were synthesized by a sol-gel method using propylene oxide as a gelation agent. Owing to the high homogeneity
of the intermediate gel precursor, the usage of this epoxide method results in a substantial reduction of calcination temperature
and time as compared with the solid-state route, and a great reduction of calcination time as compared with other wet-chemistry
routes. This high homogeneity is obtained by the usage of an appropriate amount of HCl, as a catalyst that matches the rate
of hydrolysis of TEOS and the metal ions, allowing the formation of Si–O–Co bonds. 相似文献
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Karen C. O'Brien 《Tetrahedron》2005,61(26):6243-6248
Several stereoselective routes to the synthesis of (1S,3R)-t-butyldimethyl-(1-methyl-3-oxiranyl-propoxy)-silane (13a) were explored, and the use of Jacobsen's hydrolytic kinetic resolution to separate a mixture of diastereomeric epoxides was a key step in the shortest of these. As part of an approach to the total synthesis of amphidinolide T2 (2), this epoxide, corresponding to C17-C22 of the natural product, was successfully joined with an alkyne (C13-C16) by way of a nickel-catalyzed reductive coupling reaction. 相似文献
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A two-step one-pot method was established to efficiently convert up to three 2,3-alloepoxypyranoside residues to the 2,3-mannoepithiopyranosides within the β-cyclodextrin belts. 相似文献
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Kyohei SatoAtsushi Minami Toyoyuki OseHiroki Oguri Hideaki Oikawa 《Tetrahedron letters》2011,52(41):5277-5280
Enzymatic epoxide-opening cascade is one of the key biosynthetic processes for constructing structurally diverse polyethers. Here we report the first in vitro analysis of the cyclization catalyzed by two epoxide hydrolases, MonBI and MonBII involved in monensin biosynthesis, using simple epoxy-alcohols and the unprecedented synergistic effect on the epoxide-opening activity between these epoxide hydrolases. 相似文献
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Maryam Mirza-Aghayan Mahdi Alizadeh Mahdieh Molaee Tavana Rabah Boukherroub 《Tetrahedron letters》2014
A simple, efficient, and general procedure for the ring-opening of epoxides with various alcohols to give the corresponding β-alkoxy alcohols using graphite oxide (GO) as the catalyst, under very mild reaction conditions is described. The method proceeds in good to excellent yields and in short reaction times at room temperature under metal-free conditions. 相似文献
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《Tetrahedron letters》2019,60(30):2009-2013
Transesterification of methyl esters was accelerated by an in situ-generated metal-free catalyst comprising a quaternary alkylammonium salt and an epoxide. The combination of a quaternary alkylammonium acetate and glycidol is optimal, and various esters were synthesized from methyl esters with alcohols in good to excellent yield. Analysis of the catalyst solution revealed that basic species are generated by the ring-opening reaction of epoxide. 相似文献
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Ring‐opening reactions of epoxides with nitric oxide afforded syn or anti α‐hydroxy nitrates in high regio‐ and diastereoselectivities in good yields. 相似文献
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One-Carbon Homologation of α,β-Unsaturated Aldehydes: Access to α-Tertiary β,γ-Unsaturated Aldehydes
Dr. Arnaud Delbrassinne Boris Junior Takam Mba Laurent Collard Prof. Raphaël Robiette 《European journal of organic chemistry》2023,26(40):e202300765
An efficient protocol for the synthesis of enolizable α-substituted β,γ-unsaturated aldehydes is reported. The developed strategy involves two steps, epoxidation and Meinwald rearrangement, to result in a one-carbon homologation of α,β-unsaturated aldehydes enabling the insertion of a CHR unit. 相似文献
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An effective and highly chemoselective method is described for the rapid deoxygenation of different epoxides to the corresponding olefins using ZrCl4/NaI in anhydrous CH3CN, in excellent yields and with retention of relative stereochemistry. 相似文献
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Lucy Lee Maria Marti Villalba Robert B. Smith James Davis 《Electrochemistry communications》2009,11(8):1555-1558
The use of a novel epoxide label system as the basis of a new approach to monitoring thiol species relevant to animal welfare contexts is presented. The need for the development of on-site/field testing is demonstrated through the analysis of equine saliva before and after exercise and the implication of delays in the analysis process exposed. The system is selective for thiols and, in contrast to simpler labelling systems, could offer potential for speciation studies. 相似文献
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Xue-qiang Yin 《Tetrahedron letters》2005,46(44):7535-7538
Carbocyclic nucleosides substituted at the C-6′ position are receiving increasing attention. Chiral synthetic accessibility to the biologically promising 6′-β-fluoroaristeromycin is lacking. Its preparation and that of the 5′-nor analogue are described. Along the way, a new method to aristeromycin arose as an outgrowth of a requisite structure proof. 相似文献