共查询到20条相似文献,搜索用时 10 毫秒
1.
Velimir Popsavin Goran Benedekovi? Jovana Francuz Vesna Koji? Vladimir Divjakovi? 《Tetrahedron》2009,65(51):10596-3429
Enantiodivergent total syntheses of both (+)- and (−)-enantiomers of goniofufurone, 7-epi-goniofufurone and crassalactone C have been accomplished starting from d-xylose. The key steps of the synthesis of 7-epi-(+)-goniofufurone were a stereo-selective addition of phenyl magnesium bromide to a protected dialdose, and a stereospecific furano-lactone ring formation by reaction of a related hemiacetal derivative with Meldrum's acid. Synthesis of both (+)-goniofufurone and (+)-crassalactone C required a configurational inversion at C-5 in the common intermediate that was efficiently achieved under the standard Mitsunobu conditions, or alternatively through a sequential oxidation of the benzylic hydroxyl group followed by a stereo-selective reduction with borohydride. A similar approach was then applied to the synthesis of the unnatural (−)-enantiomers of goniofufurone, 7-epi-goniofufurone and crassalactone C, as well as two novel, conformationally constrained analogues of both (+)- and (−)-goniofufurone. Their in vitro antiproliferative activities against a number of human tumour cell lines were recorded and compared with those observed for the parent natural products. 相似文献
2.
A new route towards enantiopure hydroxylactones 3 and ent-3, the final chiral precursors in an enantiodivergent synthesis of (+)- and (−)-muricatacin, has been developed starting from d-xylose. 相似文献
3.
Manju Ghosh 《Tetrahedron letters》2009,50(50):7102-1119
An enantiodivergent synthesis of both enantiomers of methylenolactocin is described through stereocontrolled addition of n-pentyl magnesium bromide to two d-mannitol-derived diastereomerically related aldehydes having an α-chiral center with a β hetero atom. 相似文献
4.
A concise total synthesis of (+)-deoxocassine (1) and (−)-deoxoprosophylline (2) has been achieved for the first time from d-xylose. The key steps involved in these synthesis are alkyl Grignard reaction, SN2 substitution of mesylate by azide, Wittig reaction, and reductive amination. 相似文献
5.
A total synthesis of d-(+)-biotin is described starting from d-(+)-glucosamine using acyliminium chemistry. 相似文献
6.
Satoshi ImutaShinya Ochiai Miho KuribayashiNoritaka Chida 《Tetrahedron letters》2003,44(27):5047-5051
The total synthesis of (−)-actinobolin 2, an antipode of the natural product starting from d-glucose is described. A three-component coupling reaction of a functionalized cyclohexenone (+)-6, derived from d-glucose by way of Ferrier's carbocyclization, with vinyl cuprate and an aldehyde (R)-5 effectively constructed the carbon framework of 2 in a highly stereoselective manner. The formal synthesis of the natural enantiomer 1 from d-glucose was also achieved. 相似文献
7.
Mohammad Abrar Alam 《Tetrahedron letters》2008,49(38):5534-5536
A total synthesis of (+)-lentiginosine, a potent and selective amyloglucosidase inhibitor, is reported from a d-glucose-derived epoxide in 38% overall yield. In this synthesis, ambient conditions and readily available starting materials and reagents are used. 相似文献
8.
The enantiopure total synthesis of (−)-codonopsinine is described from commercially available l-xylose in 20% overall yield. The key steps included Julia trans olefination and cascade epoxidation-cyclisation strategies. 相似文献
9.
Hiroki Tanimoto 《Tetrahedron letters》2007,48(36):6267-6270
The stereoselective total synthesis of (+)-galanthamine (+)-1 starting from d-glucose is described. The cyclohexene ring in (+)-1 was prepared in an optically active form from d-glucose using Ferrier’s carbocyclization reaction, and the critical quaternary carbon was stereoselectively generated via chirality transfer based on the Claisen rearrangement of a cyclohexenol. The dibenzofuran skeleton was effectively constructed by the bromonium ion-mediated intramolecular cyclization of a cyclohexene possessing a phenolic ether function. After the introduction of a carbon-carbon double bond, the Pictet-Spengler type cyclization, followed by the reduction of the amide function completed the chiral synthesis of (+)-1. 相似文献
10.
Intramolecular radical cyclisation protocol on 5-hexenyl systems derived from d-xylose, was utilized for the synthesis of (+)dihydrocanadensolide, (+)-dihydrosporothriolide and their C-3 epimers, wherein a study on the impact of C-2′ stereocentre on radical cyclisation was conducted. 相似文献
11.
A short and practical procedure for the preparation of C-2 substituted polyhydroxypyrrolidines is described. The C-2 substituent is introduced by a stereoselective addition of a Grignard reagent to a 2,3,5-protected aldofuranose and the cyclization to the pyrrolidine ring system is performed through a bis-mesylation/double nucleophilic displacement sequence. The efficiency of the methodology was demonstrated by its application to the synthesis of HomoDMDP and DMDP. 相似文献
12.
Jian Gao 《Tetrahedron》2008,64(40):9377-9383
Facile routes to several enantiomerically pure flexible chiral building blocks carrying a hidden syn or anti 1,3-diol motif were developed with the inexpensive and readily available carbohydrate d-xylose as the starting material. Application of the newly developed chiral building blocks in total synthesis is exemplified through a synthesis of (2S,4S)- and (2S,4R)-avocadotriol. Both triols were selectively acetylated on the primary hydroxyl group in high yields with Novozyme 435/vinyl acetate. On the basis of comparison of the 1H NMR, optical rotation, and melting point data, the natural avocadotriol 1-monoacetate was assigned to be of (2R,4R) configuration. 相似文献
13.
Xuequan Lu 《Tetrahedron letters》2005,46(18):3165-3168
The preparations of d-ribo- and l-lyxo-phytosphingosines (1, 2) are described. Chelation-controlled addition of tetradecylmagnesium bromide to pentylidene-protected d-threitol aldehyde 6 afforded the key intermediate tetrol 7, providing the desired l-lyxo stereochemistry of phytosphingosine. Inversion at C4 of intermediate 7 provided the d-ribo stereochemistry. 相似文献
14.
Alexandros E. Koumbis Kyriaki M. DietiMyrofora G. Vikentiou John K. Gallos 《Tetrahedron letters》2003,44(12):2513-2516
A highly efficient and versatile approach was applied for the total synthesis of the marine natural products (−)-malyngolide and (+)-tanikolide from isopropylidene l- and d-erythrose, using a common strategy. 相似文献
15.
The total synthesis of (+)-epiquinamide, a novel quinolizidine alkaloid isolated from the Ecuadoran poison frog, Epipedobates tricolor is described. The key step includes a ring-closing metathesis reaction to construct both the six member rings. d-Mannitol was used as a chiral pool material. 相似文献
16.
M. Gracia García-Martín 《Polymer Degradation and Stability》2008,93(7):1370-1375
The hydrolytic degradation of a series of aregic carbohydrate-based polyamides derived from l-arabinose and d-xylose is described. These polyamides are those that are fully sugar-based (PA-SuSu), those derived from aldaric acids and polyalkylene diamines (PA-mSu), and those derived from diamine sugars and polyalkylene dicarboxylic acids (PA-Sun). Their physical properties and crystal structures depend on their constitution and the configuration of the carbohydrate-based moiety. The feasibility of the hydrolysis of these polyamides was, in general, related with such structural properties. Thus, the fully sugar-based PA-SuSu were amorphous, water-soluble materials, and were hydrolysed in water at 70 °C. PA-mSu were crystalline and more resistant to hydrolysis — they were degraded at pH 2 and 70 °C [Tg(s) 60-90 °C]. PA-Sun were amorphous and highly hygroscopic materials — they were hydrolysed in water at 37 °C [Tg(s) 25-40 °C]. 相似文献
17.
The synthesis of d-cycloserine has been successfully accomplished from the readily available d-serine through three simple and efficient routes. In each synthetic strategy, cyclization reactions are involved as the key step, and one-pot processes are employed. The simple treatment and mild reaction conditions are attractive features in this methodology. 相似文献
18.
Asymmetric synthesis of both d- and l-isomers of 5-thioglucose and 1,6-anhydro-5-thioaltrose are described. The key intermediates, l- and d-threose diethylacetal derivatives, were derived by chemical transformation from d-xylose or d-arabinose and by Sharpless asymmetric dihydroxylation from γ-hydroxycrotylaldehyde diethylacetal. They transformed to γ-thiiranyl diethylacetal via trans-2,3-epoxy alcohol in seven steps. Acetic acid-promoted cyclization of γ-thiiranyl diethylacetal gave 5-thiopyranoside. Removal of the protected groups under the acidic conditions afforded 5-thio-d- and l-glucose and 1,6-anhydro-5-thio-l- and d-altrose, respectively. 相似文献
19.
The total synthesis of the actin-targeting metabolite (−)-microcarpalide is described. Ring-closing metathesis of a dienic ester was used as the key step. d-Mannitol was used as the chiral pool material for the construction of the olefinic acid moiety as well as the olefinic alcohol moiety of the molecule. 相似文献
20.
A preparative and short synthesis of l-ribose and l-apiose was accomplished starting from d-ribose via stereoselective cis-dihydroxylation and C2-hydroxymethylation, respectively. These l-sugars can serve as versatile intermediates for the synthesis of l-nucleosides. 相似文献