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1.
The first total synthesis of (+)-tricycloclavulone having a unique tricyclo[5,3,0,01,4]decane skeleton and six chiral centers was achieved in a highly stereoselective manner. It includes a catalytic enantioselective [2+2]-cycloaddition reaction using novel chiral copper catalyst, extremely effecting an intramolecular ester transfer reaction, and asymmetric reduction of the carbonyl group on the alpha-chain using Noyori's chiral ruthenium catalyst.  相似文献   

2.
The first enantioselective total synthesis of (+)-phakellstatin and (+)-dibromophakellstatin was achieved. Key steps in the synthesis were a desymmetrization of the diketopiperazine (S,S)-cyclo (Pro, Pro) via a diastereoselective acylation, an intramolecular Mitsunobu reaction to introduce the C6 aminal, and a tandem Hofmann rearrangement/cyclization to simultaneously introduce the C10 quaternary aminal center and deliver the cyclic urea. The synthesis also demonstrates the unusual stability of pyrrolo aminals. Importantly, this strategy has the potential for producing phakellstatin derivatives, derived from (R,R)-cyclo (Pro, Pro), necessary for biological studies. A similar annulation protocol is also expected to be applicable to the synthesis of palau'amine.  相似文献   

3.
Varseev GN  Maier ME 《Organic letters》2007,9(8):1461-1464
[reaction: see text] The enantioselective total synthesis of (+)-neosymbioimine was accomplished in 18 steps from (-)-(S)-citronellol utilizing an organocatalytic alpha-oxidation of aldehyde 6. The carbon core was constructed by a tandem Horner-Wadsworth-Emmons (HWE) reaction and an intramolecular Diels-Alder cyclization. All double bonds of 12 were made in a stereoselective manner by Wittig-type reactions. Selective formation of the monosulfate monoester was accomplished by one-pot excessive sulfation followed by kinetic hydrolysis of bissulfate 18 in 79% yield.  相似文献   

4.
《中国化学快报》2022,33(4):2044-2046
A catalytic asymmetric total synthesis of (+)-vincamine is presented. Key features of the synthesis include a Pd-catalyzed enantioselective decarboxylative allylation to form the C20 quaternary stereogenic center and a stereoselective iminium reduction to install the critical cis-C20/C21 relative stereochemisty.  相似文献   

5.
The first total synthesis of (+)-amabiline, an unsaturated pyrrolizidine alkaloid from Cynoglossum amabile, is reported. This convergent, enantioselective synthesis proceeds in 15 steps (10-step longest linear sequence) in 6.2% overall yield and features novel methodology to construct the unsaturated pyrrolizidine or (-)-supinidine core.  相似文献   

6.
An enantioselective total synthesis of (+)-digitoxigenin is described. This total synthesis is accomplished in a convergent manner using two chiral fragments prepared via the catalytic asymmetric intramolecular cyclopropanation and baker’s yeast mediated reduction developed by us, respectively. This convergent synthesis would be useful for preparing some new derivatives of digitoxigenin for SAR studies and could be applied for the total synthesis of other cardenolides left unprepared.  相似文献   

7.
The first enantioselective total synthesis of (+)-sarcodictyenone is described [4.3% overall yield from (5R,6R)-6-methyl-5-trimethylsily-2-cyclohexenone]. This work establishes the absolute stereochemistry of the natural product.  相似文献   

8.
A total synthesis of the laurencia metabolite (+)-obtusenyne has been completed. The key steps include a Sharpless kinetic resolution and an asymmetric glycolate alkylation to establish the stereogenic centers adjacent to the ether linkage and a ring-closing metathesis reaction to construct the nine-membered ether without the aid of a cyclic conformational constraint. The synthesis was completed in 20 linear steps from commercially available 1,5-hexadiene-3-ol.  相似文献   

9.
Sato T  Aoyagi S  Kibayashi C 《Organic letters》2003,5(21):3839-3842
[reaction: see text] The enantioselective total syntheses of (+)-azimine and (+)-carpaine have been developed, starting with (S)-1,2,4-butanetriol as a single source of chirality. The key common feature in these syntheses involves stereoselective intramolecular hetero-Diels-Alder reaction of an acylnitroso compound. The critical macrocyclic dilactonization of the N-Cbz derivatives of azimic acid and carpamic acid was efficiently achieved by using the Yamguchi macrocyclization conditions.  相似文献   

10.
11.
[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   

12.
The first total synthesis of gliocladin C, a fungal-derived marine alkaloid containing a rare trioxopiperazine fragment, is reported. This asymmetric synthesis establishes the absolute configuration of this structurally novel natural product. [reaction: see text].  相似文献   

13.
Shan Qian  Gang Zhao 《Tetrahedron》2013,69(52):11169-11173
An enantioselective total synthesis of the lindenane sesquiterpene (+)-sarcandralactone A has been accomplished for the first time. The synthesis features a SeO2-mediated [2,3]-sigmatropic rearrangement for the facile construction of the tertiary allylic alcohol as a single diastereoisomer.  相似文献   

14.
An enantioselective total synthesis of the diterpenoid natural product (+)-salvileucalin B is reported. Key findings include a copper-catalyzed arene cyclopropanation reaction to provide the unusual norcaradiene core and a reversible retro-Claisen rearrangement of a highly functionalized norcaradiene intermediate.  相似文献   

15.
《Tetrahedron letters》1988,29(45):5767-5768
Enantioselective total synthesis of (+)-monomorine I was achieved starting from diethyl L-tartrate via 1,2-asymmetric induction based on highly diastereoselective hydride addition to acyclic α,β-dialkoxy ketones.  相似文献   

16.
[structure: see text] A stereoselective synthesis of SCH 351448 has been completed. Twelve of the fourteen stereogenic centers were established through chiral enolate reactions, and six key C-C bonds were formed by metathesis reactions.  相似文献   

17.
[reaction: see text] The enantioselective synthesis of the (+)-leucascandrolide A macrolactone has been achieved in 20 linear steps from 1,3-propanediol. The key steps in the synthesis are a reductive cleavage of bicyclic ketal 5 to establish the C15 stereogenic center and a diastereoselective aldol of the boron enolate of methyl ketone 3 to aldehyde 4 in preparation for a heteroconjugate addition for the introduction of the C3 stereocenter.  相似文献   

18.
《Tetrahedron: Asymmetry》2001,12(1):95-100
A concise and efficient total synthesis of (+)-3,4-epoxycembrene-A 1, an epoxy cembrane diterpenoid from tropical marine soft coral, is described. The synthesis features the use of an intramolecular McMurry coupling and Sharpless asymmetric epoxidation as key steps.  相似文献   

19.
An expedient enantioselective synthetic approach for the gypsy moth sex-attractant pheromone cis-(+)-1 and trans-(+)-disparlure 2 is described employing the optimized combination of organocatalytic MacMillan’s self aldol reaction, Wittig olefination, regioselective ring opening of an epoxide and Mitsunobu esterification reactions as key steps.  相似文献   

20.
An enantioselective first total syntheis of amphidinolide W (2) and a revision of its C6 absolute stereochemistry (1) are described. Amphidinolide W (1), a 12-membered macrolide isolated from Amphidinium sp., has shown potent antitumor properties against a variety of NCI tumor cell lines. The synthesis is convergent, and four of the five chiral centers were derived through asymmetric synthesis. The synthesis features Sharpless asymmetric dihydroxylation, diastereoselective alkylation, efficient cross metathesis of functionalized substrates, and novel functional group transformations using selective lipase-catalyzed hydrolysis of the primary acetate group. Of particular note, the C6 absolute stereochemistry of amphidinolide W (1) has now been revised through our current synthesis.  相似文献   

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