共查询到20条相似文献,搜索用时 15 毫秒
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Hoffmann RW 《Angewandte Chemie (International ed. in English)》2003,42(10):1096-1109
After more than a quarter of a century of development, the methodology of stereoselective synthesis appears to be fully matured. In line with this, the potential that meso compounds offer in stereoselective synthesis is clearly recognized. The use of meso compounds in synthesis is, however, in no way commensurate with this potential, because, ironically, the synthesis of meso compounds in the first place is a problem of stereoselective synthesis. Present-day methodology does not provide many useful solutions to this problem. This Review therefore addresses the strategies available for the synthesis of more elaborate meso compounds whose stereogenic centers have a distance >1,4 between them. meso Compounds with more than four stereogenic centers are also considered. The criteria used in choosing from several strategies in the synthesis of such compounds are discussed. 相似文献
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Matthew HasslerYi Qiao Wu N. Mallikarjuna ReddyTak Hang Chan Masad J. Damha 《Tetrahedron letters》2011,52(20):2575-2578
The solid-phase synthesis of oligoribonucleotides using dimer and trimer phosphoramidite blocks is described. This method significantly reduces the total number of steps required in the synthesis of a target RNA sequence, provides more material, and simplifies separation of the product from shorter failure sequences. The procedure is illustrated by the synthesis of UpU, ApA, and UpUpU phosphoramidite blocks and their use in the rapid synthesis of oligoribonucleotides on a solid support. Dimer and trimer amidite blocks will likely find use in the large scale solution (or solid)-phase synthesis of siRNA drugs. 相似文献
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The classical Hantzsch reaction is one of the simplest and most economical methods for the synthesis of biologically important and pharmacologically useful 1,4-dihydropyridine derivatives. Bismuth nitrate pentahydrate under microwave irradiation is proven to act as a very efficient catalyst for a one-pot, three-component synthesis of 1,4-dihydropyridines in excellent yields from diverse amines/ammonium acetate, aldehydes and 1,3-dicarbonyl compounds within 1-3 min under solvent-free conditions. The present environmentally benign procedure for the synthesis of 1,4-dihydropyridines is suitable for library synthesis and it will find application in the synthesis of potent biologically active molecules. The excellent yield and extreme rapidity of the method is due to a concurrent effect of the catalyst and microwave irradiation. 相似文献
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Cascade Multicomponent Synthesis of Indoles,Pyrazoles, and Pyridazinones by Functionalization of Alkenes
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Dr. Kiran Matcha Dr. Andrey P. Antonchick 《Angewandte Chemie (International ed. in English)》2014,53(44):11960-11964
The development of multicomponent reactions for indole synthesis is demanding and has hardly been explored. The present study describes the development of a novel multicomponent, cascade approach for indole synthesis. Various substituted indole derivatives were obtained from simple reagents, such as unfunctionalized alkenes, diazonium salts, and sodium triflinate, by using an established straightforward and regioselective method. The method is based on the radical trifluoromethylation of alkenes as an entry into Fischer indole synthesis. Besides indole synthesis, the application of the multicomponent cascade reaction to the synthesis of pyrazoles and pyridazinones is described. 相似文献
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己二酸是工业上具有重要应用的二元羧酸,其合成方法的研究受到了广泛的关注.其传统的合成方法对环境造成了极大的破坏.利用含钨化合物作为催化剂催化合成己二酸是一种绿色环保的新方法,引起了人们的重视.作者介绍了近年来含钨化合物催化合成己二酸的研究进展,分析比较了不同催化剂体系的研究情况,展望了今后己二酸合成的发展前景. 相似文献
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Malcolm W.B. McCulloch 《Tetrahedron letters》2005,46(44):7619-7621
The first synthesis of the natural product guieranone A is described, demonstrating a one-pot procedure for the synthesis of protected-1,3,6,8-tetraoxygenated naphthalenes and a subsequent directed metalation synthesis of 2-keto naphthalenes. 相似文献
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Diana Meneses Souza Luciana Lucas Machado Angelo Henrique Lira Machado 《Tetrahedron letters》2019,60(28):1811-1813
The first total synthesis of (±)-floribundane B is reported. Johnson-Claisen rearrangement of a Morita-Baylis-Hillman adduct assembled all of the stereochemical features of this secoiridoid. The formal synthesis of (±)-oleocanthal and the synthesis of a chemical constituent of olive press juice is also reported. 相似文献
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Radical rearrangements are important transformations in organic synthesis. The stabilisation of alpha-nitrogen radicals is shown to be a useful effect for the control of radical rearrangements and is applied to the synthesis of a variety of azabicyclic frameworks. The utility of this method is illustrated in the synthesis of bioactive targets. 相似文献
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A concise and improved stereoselective synthesis of (+)-eleutherin, (+)-allo-eleutherin and the formal synthesis of (+)-nocardione B is described. The synthesis is based on a Dötz benzannulation and an improved oxa-Pictet-Spengler cyclization as the key steps. The synthesis is achieved in six steps in overall yields of 18% for eleutherin and 20% for allo-eleutherin. 相似文献
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A short enantioselective synthesis of (+)-eleutherin, (+)-allo-eleutherin and the formal synthesis of (+)-nocardione B is described. The synthesis is completed in six steps in overall yields of 8% for eleutherin and 14% for allo-eleutherin. The synthetic strategy features an efficient combination of the Dötz annulation reaction with a chiral alkyne and an oxa-Pictet Spengler reaction as the keys steps in the stereodivergent synthesis of (+)-eleutherin and (+)-allo-eleutherin. The synthesis of (S)-(+)-2-(2′-hydroxypropyl)-5-methoxy-1,4-naphthoquinone entails the formal synthesis of (+)-nocardione B. 相似文献
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Murai K Morishita M Nakatani R Kubo O Fujioka H Kita Y 《The Journal of organic chemistry》2007,72(23):8947-8949
The first asymmetric total synthesis of spongotine A is described. The oxidative synthesis of the imidazoline/ketone unit from keto aldehyde and diamine is a key step in this synthesis. The absolute stereochemistry of the asymmetric center of natural spongotine A is revealed as the (S)-configuration. 相似文献
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A stereoselective synthesis of (+)-herboxidiene is described. The convergent synthesis utilized a Suzuki cross-coupling reaction to assemble the key segments. The synthesis of the functionalized tetrahydropyran ring utilized an Achmatowicz reaction as the key step. The synthesis of the C10-C19 segment was accomplished using Brown's crotylboration, asymmetric alkylation, and a stereoselective allylic chlorination reactions. 相似文献
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A concise asymmetric synthesis of (-)-halenaquinone is described. The synthesis features a diastereoselective Heck cyclization to set a quaternary center as well as a novel intramolecular inverse-electron-demand Diels-Alder reaction involving a vinyl quinone. The synthesis is highly convergent and features a minimal amount of protecting group manipulations. 相似文献
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Peptide thioesters play a key role in convergent protein synthesis strategies such as native chemical ligation, traceless Staudinger ligation, and Ag(+) -mediated thioester ligation. The Boc-based solid-phase synthesis provides a very reliable access to peptide thioesters. However, the acid lability of many peptide modifications and the requirements of most parallel peptide synthesizers call for the milder Fmoc-based solid-phase synthesis. The Fmoc-based synthesis of peptide thioesters is more cumbersome and typically proceeds with lower yields than the synthesis of peptide acids and peptide amides. The success of native chemical ligation and related technologies has sparked intensive research effort devoted to the development of new methods. The recent progress in this rapidly expanding field is reviewed. 相似文献
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[structure: see text] The total synthesis of the polyether antibiotic ionomycin, a calcium ionophore, is described. The synthesis demonstrates the utility of ring-opening methodologies as applied to the synthesis of polypropionate and deoxypolypropionate subunits, which are found in two of the four fragments in the synthesis. 相似文献
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Goard M Aakalu G Fedoryak OD Quinonez C St Julien J Poteet SJ Schuman EM Dore TM 《Chemistry & biology》2005,12(6):685-693
The regulation of protein synthesis is vital for a host of cell biological processes, but investigating roles for protein synthesis have been hindered by the inability to selectively interfere with it. To inhibit protein synthesis with spatial and temporal control, we have developed a photo-releasable anisomycin compound, N-([6-bromo-7-hydroxycoumarin-4-yl]methyloxycarbonyl)anisomycin (Bhc-Aniso), that can be removed through exposure to UV light. The area of protein synthesis inhibition can be restricted to a small light-exposed region or, potentially, the volume of two-photon excitation if a pulsed IR laser is the light source. We have tested the compound's effectiveness with an in vitro protein-translation system, CHO cells, HEK293 cells, and neurons. The photo-released anisomycin can inhibit protein synthesis in a spatially restricted manner, which will enable the specific inhibition of protein synthesis in subsets of cells with temporal and spatial precision. 相似文献
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《Tetrahedron letters》1987,28(38):4469-4472
We describe a simple manually operated synthesizer for solid-phase peptide synthesis (SPPS). The synthesis is performed on standard polystyrene-based resin in a flow reactor under low-pressure conditions. The usefulness of the present configuration of SPPS is exemplified on the synthesis of two octapeptide and one decapeptide amides. 相似文献