共查询到20条相似文献,搜索用时 31 毫秒
1.
Bibigul T. Utenova 《Tetrahedron letters》2004,45(22):4233-4235
(+)-Agelasine D, originally isolated from the marine sponge Agelas nakamurai, is synthesized for the first time. The terpenoid side chain was readily available from the diterpene alcohol (+)-manool. 相似文献
2.
Gonzalo Blay 《Tetrahedron》2007,63(39):9621-9626
1αH,7αH,10αH-Guaia-4,11-dien-3-one and its 1βH,10βH diastereomer, easily obtained from (+)-dihydrocarvone, are good starting materials for the synthesis of natural guaiane derivatives. Allylic oxidation of the 1αH,10αH isomer gave as main product its 13-hydroxy derivative and a small amount of (+)-7β-hydroxy-1αH,10αH-guaia-4,11-dien-3-one, whereas the 1βH,10βH diastereomer afforded selectively the (−)-7α-hydroxy-1βH,10βH enantiomer in excellent yield. From the 13-hydroxy derivative (+)-pechueloic acid and (+)-methyl pechueloate were synthesized. Deoxygenation at C3 of the 1βH,10βH guaiadienone afforded a guaiadiene with the reported structure for aciphyllene but its spectral data did not agree with those reported for the natural diene. The structure of natural (+)-aciphyllene has been corrected to 1αH,7αH,10αH-guaia-4,11-diene obtained by deoxygenation of the 1αH,10αH guaiadienone. 相似文献
3.
Suguru Ito 《Tetrahedron》2008,64(42):9879-9884
The asymmetric total syntheses of (+)-curcutetraol and (+)-sydonol, phenolic bisabolane-type sesquiterpenoids having chiral tertiary alcohol moiety in the o-position of a phenol, were achieved in high enantiomeric excesses (99% ee). The chiral tertiary benzylic alcohol moiety of these compounds was constructed by an asymmetric synthesis using an easily available chiral aminal, (−)-(2R,5S)-2-methoxycarbonyl-3-phenyl-1,3-diazabicyclo[3.3.0]octane. The absolute configurations of both (+)-curcutetraol and (+)-sydonol have been assumed to be S-configuration based on the stereochemical course of the well established asymmetric synthesis used in the syntheses. 相似文献
4.
A new and more efficient route for the conversion of the readily available (+)-Δ3-carene into (+)-trans-chrysanthemic acid is described. 相似文献
5.
Yanli Zhang Xiaojing Liu Feng Shui Faling Zhou Jing Cui Xiaochuan Chen 《Tetrahedron letters》2019,60(27):1784-1787
The concise and efficient synthesis of (+)-goniofufurone, (+)-7-epi-goniofufurone, (+)-crassalactones B and C were achieved in 6 to 7 steps from the known d-glucono-δ-lactone derivative 9. An acid-mediated cascade cyclization was employed to construct the furanofurone bicyclic framework in one-pot. 相似文献
6.
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
7.
《Tetrahedron letters》1988,29(7):791-794
The first total syntheses of (+)-7-deoxynogarol (2) and (+)-7-con-O-methylnogarol (3), the notable members of nogalamycin congeners, were achieved employing the Diels-Alder reaction of the highly functionalized dienes (11 and 20) with the (+)-naphthoquinone (6), the CDEF-ring system of nogalamycin congeners, as a key synthetic step. 相似文献
8.
Hongbo Wei Hongli Zhang Shoule Han Shan Mu Ke Huang Guzhou Chen Weiqing Xie 《Tetrahedron letters》2019,60(35):150973
Asymmetric synthesis of the marine nor-sesquiterpenoid (+)-austrodoric acid and (+)-austrodoral in seven and nine steps respectively from Wieland-Miescher ketone was described herein. The synthesis featured an oxidative ring contraction of α-formyl cyclic ketone mediated by H2O2 to forge the hydrindane scaffold together with the contiguous quaternary carbon centers simultaneously. 相似文献
9.
Renata Kolano? Teresa Borowiak Grzegorz Dutkiewicz 《Journal of Molecular Structure》2005,737(1):75-81
The X-ray and spectroscopic results clearly indicate that the (+)-2-thiono-17-oxosparteine (1) and (+)-2,17-ditihionosparteine (2) are conformationally rigid. In order to analyze deviations of lactam/thiolactam groups from planarity induced by ring constraints, the Dunitz-Winkler approach has been used. The lactam and thiolactam groups are close to planarity, only the lactam group in one of the two independent molecules of 1 is markedly non-planar. The bond angles in the thiolactam and lactam groups are highly diverse. Rings A and C adopt a distorted sofa conformation in both compounds. The distortions in the molecules of 2 as compared with those in the related monothiolactams correspond to the unusual chemical shifts of H5(eq), H5(ax) and H11, as well as to the extremely low J5ax-6 and extremely large J5eq-6 coupling constants. Also chemical shifts show a similar regularity being extremely high and low for C2 and C17, respectively. 相似文献
10.
Sequential Baylis-Hillman/ring-closing metathesis (RCM) approach toward the total synthesis of (+)-MK7607 and (+)-streptol starting from (R,R)-tartaric acid is reported. 相似文献
11.
《Tetrahedron: Asymmetry》1999,10(2):297-306
A formal synthesis of (+)-vincamine (1) from (S)-(+)-2-ethyl-2-(2-methoxycarbonylethyl) cyclopentanone (6a) is described. This intermediate had previously been obtained by our research group in 90% ee through d'Angelo's deracemizing alkylation of the chiral imine 7, easily prepared from (R)-(+)-α-methylbenzylamine and 2-ethyl cyclopentanone with methyl acrylate. A potencial advanced intermediate for the synthesis of (+)-4, an epimer of (+)-1 at positions C-3 and C-14, has also been prepared from 6a. 相似文献
12.
Short syntheses of bioactive (+)-ferruginol in five or six synthetic steps starting from commercially available (+)-dehydroabietylamine are described. The oxygenated function at C12 was introduced via a Friedel-Crafts acylation of N-phthaloyldehydroabietylamine followed by Baeyer-Villiger oxidation. Then, overall deprotection of functional groups, reductive deamination or biomimetic oxidative deamination, and final Wolff-Kishner reduction provided (+)-ferruginol in 21 and 23% overall yields, respectively. 相似文献
13.
Rodney A. Fernandes Mahesh B. Halle Asim K. Chowdhury Arun B. Ingle 《Tetrahedron: Asymmetry》2012,23(1):60-66
A diastereoselective synthesis of (+)-nephrosterinic acid and (+)-protolichesterinic acid, common members of the paraconic acids is described. The synthesis is based on a diastereoselective orthoester Johnson–Claisen rearrangement of a (Z)-allyl alcohol with a vicinal dioxolane moiety as key steps. The synthesis is completed in 10 steps and with overall yields of 15.9% for (+)-nephrosterinic acid and 16.4% for (+)-protolichesterinic acid. 相似文献
14.
Daisuke MatsumuraToshimasa Takarabe Takumi TodaTakashi Hayamizu Kiyoto SawamuraKen-ichi Takao Kin-ichi Tadano 《Tetrahedron》2011,67(35):6730-6745
The total syntheses of both natural (+)-spiculoic acid A and (+)-zyggomphic acid, new cytotoxic marine natural products of polyketide origin, have been accomplished for the first time. These syntheses were achieved by the highly stereoselective and high-yielding intramolecular Diels-Alder reaction of a functionalized (E,E,E)-2,7,9-dodecanal derivative to construct the core tetrahydroindan-2-one skeleton. A stereocongener of (+)-spiculoic acid A, i.e., the (2R,5S,6R)-isomer, was also synthesized. The details of these total syntheses are described. 相似文献
15.
Pinki PalArun K. Shaw 《Tetrahedron》2011,67(22):4036-4047
Stereoselective total syntheses of aggregation pheromones (+)-exo-brevicomin (9a), (−)-exo-brevicomin (9b), (+)-endo-brevicomin (9c), (−)-endo-brevicomin (9d) and styryllactones (+)-cardiobutanolide (14a), (−)-cardiobutanolide (14b), and (+)-goniofufurone (19a) were achieved in good yields from enantiomerically pure highly functionalized furanoid glycal building blocks (1a-d) involving similar synthetic strategies, thus making these furanoid glycals highly useful building blocks in diversity-oriented synthesis (DOS). 相似文献
16.
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
17.
We present a divergent strategy for the stereoselective synthesis of both eudesmanolides (+)-tuberiferine and (+)-brachylaenolide starting from the accessible germacrolide (+)-costunolide. The key steps of these syntheses are the Ti-catalyzed transannular cyclization of a 1,4-epoxygermacrolide in the presence or absence of water, respectively. The catalytic cycle operating in the presence of water probably involves the reduction of a tertiary radical by H-atom transfer from aquacomplex Cp2TiIII(OH2)Cl. The catalytic cycle under anhydrous conditions presumably occurs through mixed disproportionation between a tertiary radical and Cp2TiIIICl. Synthetic (+)-tuberiferine and (+)-brachylaenolide displayed an antifungal potency against Phycomyces blakesleeanus comparable or even higher than amphotericin B, the gold standard for antifungal therapy. 相似文献
18.
Divya Tripathi 《Tetrahedron letters》2008,49(49):7012-7014
A versatile and efficient method for the enantioselective synthesis of 2,7-cis-disubstituted oxepane 1c, (+)-isolaurepan, using oxidative resolution of a secondary alcohol and highly diastereoselective Et3SiH/TMSOTf-promoted reductive cyclization of a hydroxy ketone is described. 相似文献
19.
Xiaoyu Li Xiaozhen JiaoXiaoyu Liu Chengsen TianLiang Dong Yangyang YaoPing Xie 《Tetrahedron letters》2014
A practical total synthesis of the natural products (+)-isogalbulin and (+)-galbulin has been achieved in 10 steps from readily available 3-(3,4-dimethoxyphenyl)propanoic acid. The total yields were 12.3% and 12.9%, respectively. The key steps involved Evans asymmetric alkylation, Sharpless asymmetric epoxidation, and a highly regioselective opening of 1-benzyloxy-2,3-epoxides with an organoaluminum ate-complex formed by Me3Al and n-BuLi. 相似文献
20.
The combined use of the Sharpless asymmetric epoxidation, a number of stereospecific chemical transformations, and the 3,5-hexadienoic acid benzannulation protocol allowed us to devise a new, divergent, and stereoselective approach to terpenes with a chiral tertiary hydroxyl group at the ortho-position of a phenol functional group. Accordingly, the natural occurring enantiomeric forms of the bisabolane sesquiterpenes (+)-curcutetraol, (+)-sydonol, (+)-sydonic acid, and (+)-7-O-methylsydonic acid were synthesized with high enantiomeric purity starting from geraniol. The latter two acids were prepared in enantioenriched form for the first time. 相似文献