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1.
The synthesis of heliannuol D along with the first synthesis of heliannuol B has been achieved using Mitsunobu reaction and ring-closing metathesis as the key steps. 相似文献
2.
Alibés R Bayón P de March P Figueredo M Font J García-García E González-Gálvez D 《Organic letters》2005,7(22):5107-5109
[reaction: see text] A highly versatile approach to the enantioselective synthesis of securinega alkaloids is presented. Crucial steps are a palladium-catalyzed enantioselective imide alkylation, a vinylogous Mannich reaction, and a ring-closing metathesis process. Through this strategy, the synthesis of (-)-norsecurinine has been accomplished in nine steps and 11% overall yield. 相似文献
3.
The first efficient asymmetric synthesis of obolactone 1 has been accomplished in 11 steps and with a 15% overall yield in which Brown's enantioselective allylation reactions and ring-closing metathesis reaction are key steps. 相似文献
4.
The first enantioselective synthesis of (+)-hygrine (1) is reported. 1 was obtained in 12 steps with 29% overall yield and 97% ee via asymmetric phase-transfer catalytic alkylation and ring-closing metathesis as key steps. The absolute configuration of (+)-hygrine could be directly confirmed as R. 相似文献
5.
Subir K. Sabui 《Tetrahedron letters》2004,45(10):2047-2048
A facile, very short synthesis of the allelochemical heliannuol D is described involving the application of ring-closing metathesis to generate the benzoxepane ring system of 1. 相似文献
6.
The first enantioselective total synthesis of clavirolide C, a member of the dolabellane family of diterpenes isolated from Pacific soft coral Clavularia viridis, is disclosed. The total synthesis features the application of chiral amino acid based ligands in Cu-catalyzed asymmetric conjugate addition (ACA) reactions and a relatively rare application of catalytic ring-closing metathesis to access an 11-membered ring structure. The total synthesis effort has spawned the development of a new protocol for NHC.Cu-catalyzed ACA of alkylaluminum reagents to beta-substituted cycloalkenones. The enantioselective clavirolide C synthesis requires 17 steps (longest linear sequence), affords the target molecule in 3.5% overall yield, and confirms the stereochemical assignment for the natural product. 相似文献
7.
Kong J Chen CY Balsells-Padros J Cao Y Dunn RF Dolman SJ Janey J Li H Zacuto MJ 《The Journal of organic chemistry》2012,77(8):3820-3828
A highly efficient synthesis of Vaniprevir (MK-7009) has been accomplished in nine linear steps and 55% overall yield. The key features of this synthesis include a cost-effective synthesis of the isoindoline subunit and efficient construction of the 20-membered macrocyclic core of Vaniprevir (MK-7009) utilizing ring-closing metathesis technology. A high-performing ring-closing metathesis protocol has been achieved by simultaneous slow addition of the ruthenium catalyst (0.2 mol %) and the diene substrate at a concentration of 0.13 M. 相似文献
8.
[reactiojn: see text] The enantioselective synthesis of (+)-rogioloxepane A has been achieved in 21 steps from 1,5-hexadien-3-ol. The key steps in the synthesis are an asymmetric glycolate alkylation leading to the diene 2 and a subsequent ring-closing metathesis to construct the oxepene core. 相似文献
9.
The convergent enantioselective synthesis of a protected C1-C18 building block for the total synthesis of (-)-lytophilippine A was achieved. A catalytic asymmetric Gosteli-Claisen rearrangement and an Evans aldol reaction served as key C/C-connecting transformations during the assembling of the C1-C7 subunit (10 steps from 4, 29%). The synthesis of the C8-C18 segment was achieved utilizing d-galactose as inexpensive ex-chiral-pool starting material (15 steps, 15%). The merger of the subunits was accomplished by a remarkably efficient sequence consisting of esterification and ring-closing metathesis (five steps, 56%). 相似文献
10.
Haack T Haack K Diederich WE Blackman B Roy S Pusuluri S Georg GI 《The Journal of organic chemistry》2005,70(19):7592-7604
[reaction: see text] Two formal total syntheses of the (-)-salicylihalamides, based on chiral pool approaches, are reported. D-glucose and L-rhamnose were used to prepare advanced intermediates 23 and 54, which can be converted in three or four steps, respectively, to the target compounds. The synthesis of 23 from a known D-glucose-derivative was accomplished in 12 steps and 17% overall yield, and the synthesis of 54 from a known L-rhamnose-derivative was done in nine steps and 6% overall yield. A key step in the synthesis was a ring-closing metathesis reaction to prepare the macrocyclic ring system. It was demonstrated that the phenolic protecting group was critical for inducing the preferential formation of the desired E isomer. It was further shown that the protecting group at the C13 hydroxyl group had no significant influence on the E:Z ratio during the ring-closing metathesis reaction. 相似文献
11.
A high-yielding N-sulfonyliminium ion-enoxysilane cyclization and a ring-closing metathesis are key steps in the enantioselective synthesis of late-stage intermediates en route to sarain A. Also revealed is an unprecedented rearrangement of the tetracyclic sarain A core under mildly acidic conditions. [structure: see text] 相似文献
12.
Evans PA Cui J Gharpure SJ Polosukhin A Zhang HR 《Journal of the American Chemical Society》2003,125(48):14702-14703
The enantioselective total synthesis of the annonaceous acetogenin (-)-mucocin (1) was accomplished using a triply convergent 12-step sequence (longest linear sequence) in 13.6% overall yield. This represents the first application of the temporary silicon-tethered (TST) ring-closing metathesis (RCM) cross-coupling reaction and the enantioselective alkyne/aldehyde addition to the synthesis of a complex annonaceous acetogenin. Moreover, all three fragments required for the coupling reactions are conveniently prepared in 5-6 steps from two readily available enantiomerically enriched epoxides. Finally, this synthesis stimulated the development of a new approach for the construction of 3-hydroxy-2,6-disubstituted tetrahydropyrans, using the bismuth tribromide-mediated reductive etherification reaction, which represents a motif that is prevalent in a wide range of pharmacologically significant natural products. 相似文献
13.
An enantioselective synthesis of the piperidine alkaloids (+)-sedamine and (-)-prosophylline is reported. The synthesis of (+)-sedamine has been achieved in 12 steps with an overall yield of 20% from benzaldehyde, and (-)-prosophylline was obtained in 15 steps with an overall yield of 9.2%, starting from D-glyceraldehyde acetonide 14. The key steps are enantioselective allyltitanation reactions and ring-closing or cross-metathesis reactions. 相似文献
14.
A regio- and stereocontrolled total synthesis of (-)-allosamizoline is described. The key steps for this synthesis are ring-closing metathesis to form the cyclopentene core, halocyclization to afford the oxazoline ring, and finally stereoselective alkene radical addition followed by an alkene isomerization reaction to install the hydroxymethyl group. (-)-Allosamizoline was prepared in a total of 13 steps and 22% overall yield. 相似文献
15.
《Tetrahedron: Asymmetry》2006,17(3):325-329
An asymmetric synthesis of herbarumin III has been developed using (R)-cyclohexylidene glyceraldehyde 1 as the chiral template. The key steps of the synthesis were the enantioselective preparation of the required homoallylic alcohol from 1, an asymmetric dihydroxylation, and a ring-closing metathesis reaction for the macrolactonization. 相似文献
16.
A new enantioselective synthesis of the idolizidine alkaloid (-)-swainsonine 1 in 40% overall yield starting from the known oxazolidinone 6 is described. Throughout the synthesis, the high efficiency of metal-catalyzed reactions is illustrated. The key step is a new ruthenium-catalyzed metathesis rearrangement reaction. In this ring-closing/ring-opening tandem process, stereocenters are transferred from a ring to the olefinic side chain of the formed heterocycle. The metathesis precursor was obtained by palladium-catalyzed desymmetrization of cyclopentenediol. The synthesis was completed by functionalization of the terminal double bond, cyclization of the second ring, and diastereoselective dihydroxylation. 相似文献
17.
[structure: see text] The total synthesis of (+)-zoapatanol utilizing an intramolecular Horner-Wadsworth-Emmons olefination and an enantioselective Sharpless dihydroxylation as the key steps has been achieved. An advanced oxepene intermediate has been obtained by applying a ring-closing metathesis to an unsaturated enol ether. 相似文献
18.
Xiaoyu LiuXiaozhen Jiao Qian WuChengsen Tian Renze LiPing Xie 《Tetrahedron letters》2012,53(29):3805-3807
A practical synthesis of Entecavir (1) has been accomplished in 10 steps with 21% overall yield. The key steps to construct the five-membered carbocyclic framework 2 are a ring-closing metathesis and a diethyl-aluminum 2,2,6,6-tetramethyl piperidide (DA-TMS) mediated epoxide isomerization. Furthermore, the guanine was introduced by modified Mitsunobu reaction. 相似文献
19.
[structure: see text] The first enantioselective total synthesis of tonantzitlolone, a novel 15-membered macrocyclic diterpene, utilized a Julia olefination, a highly selective, potassium enolate-based anti-Felkin aldol reaction, and an E-selective ring-closing metathesis as key C-C bond-forming steps. The absolute configuration of tonantzitlolone is established. 相似文献
20.
An enantioselective synthesis of (-)-galanthamine has been realized in 11 linear steps starting from isovanillin. A Mitsunobu aryl ether forming reaction was used to assemble the galanthamine backbone, which was stitched together using enyne ring-closing metathesis, Heck, and N-alkylation reactions affording the tetracyclic ring system. Control of relative and absolute stereochemistry was derived from an easily accessible enantiomerically enriched propargylic alcohol 13. 相似文献