共查询到20条相似文献,搜索用时 281 毫秒
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Jennifer L. Stockdill 《Tetrahedron letters》2009,50(26):3182-8457
An unusual loss of CO was observed during a key cyclization event in efforts toward the total synthesis of zoanthenol. The synthesis of the cyclization precursor and a proposed mechanism for decarbonylation are detailed. 相似文献
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Stereoselective synthesis of the C21–C40 core segment of caylobolide A has been achieved following a highly efficient convergent strategy. The key reactions featured in the synthesis are Prins cyclization, reductive radical cyclization, Sharpless asymmetric epoxidation and olefin cross metathesis. 相似文献
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Seijiro Hosokawa 《Tetrahedron letters》2009,50(48):6701-3154
The first total synthesis and structural determination of benzopyrenomycin has been achieved. This synthesis contains remarkable transformations including cyclization to afford the benzanthrone skeleton, syn-selective vinylogous Mukaiyama aldol reaction, and radical cyclization with the benzanthrone attaching the iodoalkane chain. 相似文献
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The development of efficient methods for the indole synthesis catalyzed by Cu(II) salts and its applications were investigated. Cu(OAc)(2) has been proved to be the best catalyst for the synthesis of various 1-p-tolylsulfonyl or 1-methylsulfonylindoles, which have both electron-withdrawing and electron-donating groups on the aromatic ring and C2 position of indoles. For the primary aniline derivatives, Cu(OCOCF(3))(2) showed good activities, while Cu(OAc)(2) was a good catalyst for the cyclization of secondary anilines. This methodology could be applied to the sequential cyclization reaction for the compounds which have the electrophilic part in the same molecule. By prior treatment with KH, the sequential cyclization was realized to provide the tricyclic ring systems, but it was limited to five- and six-membered rings for the second cyclization. Finally, formal and total synthesis of hippadine with the Cu(II)-promoted indole synthesis as the key step was accomplished. 相似文献
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A new oxygen-centered radical cyclization onto silyl enol ethers has been developed and utilized for the synthesis of versatile siloxy-substituted tetrahydrofurans. The reactions display excellent chemoselectivity for cyclization onto the electron-rich silyl enol ether when competing terminal alkene cyclization, 1,5-hydrogen abstraction, and beta-fragmentation pathways are present. The increased chemoselectivity also allows for the synthesis of tetrahydropyrans, a challenging substrate class to access using oxygen-centered radical alkene cyclizations due to competing 1,5-hydrogen abstractions. 相似文献
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萘并呋喃是一类重要的有机芳杂环,其分子骨架不仅是许多天然产物、药物分子的核心结构,而且还是重要的有机合成中间体,在材料化学中也具有广泛的应用价值。因此,萘并呋喃及其衍生物的合成一直是有机合成的研究热点之一。本文将对已有的萘并呋喃类化合物的主要合成策略、方法,结合笔者课题组的部分研究工作进行综述,包括如下几个方面:(1)碱或酸促进的环化反应;(2)过渡金属催化的串联环化反应;(3)自由基引发的环化反应;(4)其他非金属催化的环化反应。最后展望了萘并呋喃衍生物合成的研究和发展方向。 相似文献
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BinFU DaMingDU QingXIA 《中国化学快报》2004,15(4):383-385
The synthesis of bis(oxazoline) dicarboxylate derivatives was investigated.Diethyl-aminosulfur trifluoride (DAST) was used as a convenient cyclization reagent in the synthesis of bis(oxazoline) dicarboxylate derivatives,which can not be obtained by the general method using MsC1 and Et3N as dehydrating cyclization reagent. 相似文献
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David R. Elmaleh Felix E. Granchelli John L. Neumeyer 《Journal of heterocyclic chemistry》1979,16(1):87-92
The synthesis of three new racemic aporphine alkaloids ( 1b, 1c and 2 ) is reported and these alkaloids are fully characterized. The method of synthesis involved either a Bischler-Napieralski-Psehorr sequence or a Reissert alkylation-Pschorr cyclization route. The Pschorr cyclization also gave the morphinandienones 7a and 7b , respectively. 相似文献
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Leonardus H. Leijendekker Jens Weweler Tobias M. Leuther Dr. Daniel Kratzert Dr. Jan Streuff 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(13):3382-3390
The exceptionally mild conditions of a titanium(III)-catalyzed cyclization reaction paired with a convenient acid/base extraction have enabled the straightforward synthesis, isolation, and direct N-functionalization of amino heterocycles such as 3-aminoindoles and -pyrroles. The unprotected heterocycles are ideal building blocks for the installation of aminated indoles and pyrroles into target molecules, but their sensitivity has previously impeded their synthesis by modern catalytic methods. This full paper presents the development and extended scope of the new cyclization methodology. The transformation of the products into fused bis-indoles is also demonstrated along with the discovery of an unusual palladium-catalyzed reductive biphenyl coupling reaction. The titanium(III)-catalyzed cyclization has also been applied to the synthesis of substituted 3-iminoindolines, which are of potential interest for applications in natural product synthesis and exhibit tunable blue-to-green fluorescence properties. 相似文献
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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
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The intramolecular cyclization reactions of aziridines with pi-nucleophiles can be a useful route to a number of heterocyclic and carbocyclic ring systems. We were particularly interested in the use of this cyclization reaction for the synthesis of 6-azabicyclo[3.2.1]octanes. We report here the development of a new synthesis of the aziridine necessary for the aziridine--pi-nucleophile cyclization. We also report on the cyclization of aziridines with three different substitutions on the aziridine nitrogen. We have found that N-diphenylphospinyl and N-H aziridines, while participating in the initial ring-opening reaction, do not lead to the desired bicyclic ring systems. In contrast, a nosyl group on the aziridine nitrogen leads efficiently to the bicyclic ring system and can be readily deprotected. 相似文献
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An approach to the synthesis of hamigeran B is described. Key steps include a Tius-Nazarov cyclization and a palladium-catalyzed oxidative cyclization of an α-hydroxyenone. 相似文献
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对近几十年来由假紫罗兰酮环化合成紫罗兰酮的研究进展作了简要的综述,重点讨论了各类酸催化剂对环化反应的影响。参考文献23篇。 相似文献
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R. Sateesh Chandra KumarG. Venkateswar Reddy K. Suresh BabuJ. Madhusudana Rao 《Tetrahedron letters》2011,52(34):4382-4384
A highly stereoselective total synthesis of (+)-(8R,8aR)-perhydro-8-indolizidinol is described. Key steps involved in this synthesis are diastereoselective zinc allylation, azido-olefin cyclization and reductive amination followed by cyclization which effectively constructed the indolizidine ring. This contributes a unique approach to the synthesis of indolizidine alkaloids that offers the advantages of brevity and relatively high overall yields. 相似文献
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A controlled synthesis strategy for a anthracene-fused perylene bisimide was developed from the cyclization of an anthracene unit pendant to a perylene diimide scaffold. The direct cyclization led to a zigzag molecule, while a Diels-Alder strategy influenced the regiochemistry of cyclization to afford the linear precursor of a new acene. 相似文献
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[formula: see text] Tetrahydropyran rings are found in many complex natural products, and the segment-coupling Prins cyclization is an effective strategy for their synthesis. We report a four-step, stereoselective synthesis of the C20-C27 tetrahydropyran segment of phorboxazole. The key step is a Prins cyclization induced by catalytic BF3.OEt2. 相似文献
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[reaction: see text] An efficient oxidative radical cyclization approach for the synthesis of 2-alkenyl cyclopentane or cyclohexane carboxylates from omega-silylallyl ester enolates induced by recyclable SET oxidant ferrocenium hexafluorophosphate has been developed. A new tandem alkoxycarbonylation/oxidative radical cyclization/cationic termination process forms the basis for a five-step synthesis of the cyclopentanoid monoterpene dihydronepetalactone and analogues. 相似文献