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1.
A common strategy for the total syntheses of the protected l-arabino- and l-ribo-C18-phytosphingosine (8 and 9, respectively), HCl salts of ent-2-epi-jaspine B (ent-6) and 3-epi-jaspine B (7) with efficient use of both flexible building blocks 26 and 27 was achieved. The key step of this approach was [3,3]-sigmatropic rearrangement of allylic trichloroacetimidate 21 and thiocyanate 22, which were derived from the known 2,3:5,6-di-O-isopropylidene-d-mannofuranose 18 as the source of chirality. The side chain functionality was installed utilizing a Wittig reaction. 相似文献
2.
G. Srinivas RaoB. Venkateswara Rao 《Tetrahedron letters》2011,52(46):6076-6079
The highly stereoselective Grignard addition on chiralimine 8 and opening of chiral epoxide 9 with Grignard reagent have been used as key steps in the stereoselective synthesis of cytotoxic anhydrophytosphingosine pachastrissamine (jaspine B) and N,O,O,O-tetra-acetyl d-lyxo-phytosphingosine. 相似文献
3.
S.Vasudeva NaiduPradeep Kumar 《Tetrahedron letters》2003,44(5):1035-1037
An enantioselective synthesis of d-ribo-C18-phytosphingosine as its tetraacetate derivative 10, starting from d-mannitol and employing the Sharpless asymmetric dihydroxylation reaction on allylic alcohol 6 as the key step, is described. 相似文献
4.
Abhishek Dubey 《Tetrahedron letters》2009,50(26):3425-9290
A concise and highly efficient synthesis of l-arabino-[2R,3S,4R] and l-xylo-[2R,3S,4S]-C18-phytosphingosines has been achieved. The synthetic strategy features the Sharpless kinetic resolution and tethered aminohydroxylation as the key steps. 相似文献
5.
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
6.
Fausta Ulgheri 《Tetrahedron》2008,64(51):11768-11775
An highly stereoselective, flexible and very short synthetic approach to d-ribo-configured ureido monosaccharides of the aldose, aldonic acid and alditol series has been performed starting from the 5-(alditol-1-C-yl)-hydantoin intermediates, obtained via aldol-type addition reaction of hydantoin based building blocks to enantiomerically pure aldehydes. A study to assess the stereoselectivity of this reaction has been undertaken and a very high increase of diastereoselectivity was observed depending on the hydantoin protecting group. The imidazolidinone ring elaboration of 5-(alditol-1-C-yl)-hydantoin intermediates to give ureido sugar derivatives was studied. 相似文献
7.
Enantiomerically pure (2S,3R,4R)-d-xylo phytosphingosine is synthesized in 36% overall yield in seven steps from known β-lactam (8) derived from d-mannitol triacetonide. 相似文献
8.
A novel approach to natural β-hydroxy-γ-lactone 2 from 2,5-anhydro-d-mannitol (1) is described. The key reactions in this synthesis include stereoselective methylation of aldehyde 3 with lithium dimethylcuprate, an intramolecular radical cyclization of seleno carbonate 11 and an intermolecular cross-metathesis of 3-allyl-4-hydroxy-γ-lactone 16 with 1-tridecene. 相似文献
9.
Starting from a single suitable functionalised epoxide, a highly efficient stereoselective synthesis of d-erythro-sphingosine and d-lyxo-phytosphingosine is described. The approach allows the formal preparation of all stereoisomers of these sphingoid structures. 相似文献
10.
Jagadish Pabba 《Tetrahedron letters》2005,46(21):3619-3622
The d-gluco-, l-ido-, d-galacto-, and l-altro-configured glycaro-1,5-lactams 1-4 were prepared from the known tartaric anhydride 5 via the aldehyde 6. These lactams are known (1) or potential (2-4) inhibitors of β-d-glucuronidases and α-l-iduronidases. Olefination of 6 to the (E)- and (Z)-alkenes 7 or 8, followed by reagent or substrate controlled dihydroxylation, lactonization, azidation, reduction, and deprotection led in 10 steps and in overall yields of 11-20% to the title lactams. 相似文献
11.
Gagik G Melikyan Steve Sepanian Ferdinand Villena Brian Ahrens John Matchett Edwin Abrenica Kenneth I Hardcastle 《Journal of organometallic chemistry》2003,683(2):324-330
The highly stereoselective synthesis of d,l-hexestrol (1), an inhibitor of microtubule assembly, is developed by using, as a key step, an intermolecular coupling of Co2(CO)6-complexed propargyl radicals. The latter are generated by novel complementary processes involving an interaction of tetrahydrofuran with Co2(CO)6-complexed propargyl alcohols and cations. An isomerically pure d,l-μ-η2-[3,4-di(4-methoxyphenyl)-1,5-hexadiyne]-bis-dicobalthexacarbonyl (d,l-6) is isolated in 69-91% yield with intermolecular coupling reactions exhibiting an excellent chemo- (0.5-7%) and d,l-diastereoselectivity (90-94%). The structure of d,l-6 is determined by X-ray diffraction. The subsequent steps include BBr3-induced demethylation of 4-methoxyaryl groups, demetalation with cerium(IV) ammonium nitrate, and hydrogenation of acetylenic termini affording d,l-hexestrol (1). 相似文献
12.
A new, simple strategy has been formulated for the synthesis of deoxyamino sugars from a non-sugar starting material. Starting from the enantiomerically pure diol obtained from ethyl sorbate by Sharpless asymmetric dihydroxylation, the synthesis of two types of 2,3,4,6-tetradeoxy-4-amino sugars—d-tolyposamine and 4-epi-d-tolyposamine—, and formal synthesis of 2,4,6-trideoxy-4-amino sugar—d-vicenisamine—were performed. 相似文献
13.
Stephen G. Davies Ai M. FletcherEmma M. Foster James A. LeePaul M. Roberts James E. ThomsonMichael A. Waul 《Tetrahedron》2014
A range of the methyl glycosides of 2-deoxy-2-aminohexoses, comprising d-allosamine, d-mannosamine, d-idosamine and d-talosamine, were prepared from the corresponding d-aldopentoses via a seven step synthetic sequence. The doubly diastereoselective conjugate addition of the requisite antipode of lithium N-benzyl-N-(α-methylbenzyl)amide and in situ enolate oxidation with the requisite antipode of camphorsulfonyloxaziridine (CSO) was used as the key, stereodefining step. Sequential reduction of the resultant α-hydroxy-β-amino esters and oxidative cleavage of the C(1)–C(2) diol unit furnished the corresponding α-amino aldehydes. Subsequent N- and O-deprotection gave the target compounds (as mixtures of anomers) in good yield and high diastereoisomeric purity. 相似文献
14.
d-ribo-C18-phytosphingosine and l-arabino-C18-phytosphingosine were synthesised starting from commercially inexpensive d-fructose. Metal-mediated fragmentation and stereoselective reduction were used as key steps to provide the hydrophilic portion of d-ribo and l-arabino phytosphingosines. Grubbs’ cross-metathesis and hydrogenation allowed the incorporation of hydrophobic tail. 相似文献
15.
Navnath B. Kalamkar 《Tetrahedron letters》2010,51(51):6745-6747
Synthesis of cis-3-hydroxy-l-proline from d-glucose is reported. The methodology involves conversion of d-glucose into N-benzyloxycarbonyl-γ-alkenyl amine which on 5-endo-trig-aminomercuration gave the pyrrolidine ring skeleton with sugar appendage in 25% yield. Alternatively, N-benzyloxycarbonyl-γ-alkenyl amine on hydroboration-oxidation, mesylation and intramolecular SN2 cyclisation afforded pyrrolidine ring compound in high yield. Hydrolysis of 1,2-acetonide functionality, NaIO4 cleavage followed by oxidation of an aldehyde into acid and hydrogenolysis afforded cis-3-hydroxy-l-proline in overall 29% yield from d-glucose. 相似文献
16.
B.Gopal ReddyYashwant D Vankar 《Tetrahedron letters》2003,44(25):4765-4767
Methyl N-acetyl-α-d-lividosaminide has been synthesised starting from 4,6-di-O-benzyl-d-glucal via a new nitro glucal derivative in six steps. 相似文献
17.
A general strategy for the synthesis of deoxyazasugars from d-glucose is described. Ring-closing metathesis and stereoselective dihydroxylation reactions were used as key steps. 相似文献
18.
The first total synthesis of the marine natural product, (S)-clavulazine has been accomplished. d-Mannitol was used as a chiral starting material. Enantioselective zinc-mediated allylation, and ring-closing metathesis are the key steps in the synthesis. Subsequent condensation followed by dehydrogenation yielded the natural product, (S)-clavulazine. 相似文献
19.
Céline Falentin 《Tetrahedron letters》2009,50(38):5364-1987
d-Ribono-1,4-lactone was treated with ethylamine in DMF to afford N-ethyl-d-ribonamide 9a in quantitative yield. Bromination of amide 9a by the system SOBr2 in DMF or PPh3/CBr4 in pyridine led, after acetylation, to epoxide 7. However, treatment of amide 9a with acetyl bromide in dioxane followed by acetylation gave 2,3,4-tri-O-acetyl-5-bromo-5-deoxyl-N-ethyl-d-ribonamide 10a. Methanolysis of 10a, with sodium methoxide, afforded the N-ethyl-d-ribonolactam 11a in 51% overall yields. Using this method, N-butyl, N-hexyl, N-dodecyl, and N-benzyl-d-ribonolactams 11b-e were obtained in good yields (48-53%). 相似文献
20.
Peng Wei 《Tetrahedron letters》2005,46(40):6901-6905
These studies describe the chemoselective deprotection of trans-fused 2N,3O-oxazolidinone derivatives of N-acetyl-β-d-glucosamine. Selective opening of the oxazolidinone ring or N-deacetylation without ring opening is demonstrated. Certain amines are shown to efficiently afford C-2 ureido sugars under mild conditions. This work demonstrates the high degree of chemoselective manipulation possible with ring-fused 2N,3O-oxazolidinone derivatives of N-acetyl-d-glucosamine. 相似文献