- Synthesis and characterization of some atypical sphingoid bases
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Sphingolipids are ubiquitous and abundant components of all eukaryotic and some prokaryotic organisms. Sphingolipids show a large structural variety not only between the different species, but also within an individual cell. This variety is not limited to alterations in the polar headgroups of e.g. glycosphingolipids, but also affects the lipophilic anchors comprised of different fatty acids on the one hand and different sphingoid bases on the other hand. The structural variations within different sphingoid bases e.g. in pathogens can be used to identify novel biomarkers and drug targets and the specific change in the profile of common and uncommon sphingolipids are associated with pathological conditions like diabetes or cancer. Therefore, the emerging field of sphingolipidomics is dedicated to collect data on the sphingolipidome of a cell and hence to assign changes therein to certain states of a cell or to pathological conditions. This powerful tool however is still limited by the availability of structural information about the individual lipid species as well as by the availability of appropriate internal standards for quantification. Herein we describe the synthesis of a variety of 1-deoxy-sphingoid bases. 1-DeoxySphingolipids have recently acquired significant attention due to its pathological role in the rare inherited neuropathy, HSAN1 but also as predictive biomarkers in diabetes type II. Some of the compounds synthesized and characterized herein, have been used and will be used to elucidate the correct structure of these disease-related lipids and their metabolites.
- Saied, Essa M.,Le, Thuy Linh-Stella,Hornemann,Arenz, Christoph
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supporting information
p. 4047 - 4057
(2018/06/30)
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- PROCESS AND INTERMEDIADES FOR THE PREPARATION OF 7-ALKYLATED STEROIDS
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A process for preparing compounds of formula (I), or a salt, solvate or stereoisomer thereof, including Fulvestrant, which process comprises free radical to a compound of formula (III), or a salt, solvate or stereoisomer thereof. The invention also refers to intermediates of said process.
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- Stereoselective total synthesis of crucigasterins A, B and D through a common intermediate
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The first stereoselective total synthesis of the marine-derived antimicrobial amino-alcohols, crucigasterins A, B and D has been accomplished through a common intermediate starting from pent-3-en-1-ol. The method involves the Sharpless asymmetric aminohyd
- Kumar, Jayprakash Narayan,Das, Biswanath
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p. 3865 - 3867
(2013/07/19)
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- Synthesis and characterization of ferroelectric liquid crystalline siloxanes containing 4-hydroxyphenyl(2S,3S)-2-chloro-3-methylvalerate
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New series of organosiloxane ferroelectric liquid crystalline materials have been synthesized, and their mesomorphic and physical properties have been characterized. These new series contain bis-siloxane or tris-siloxane unit attached to the flexible alkyl chain end of (2S,3S)-2-chloro-3-methylvalerate. The siloxane molecule induction is helpful to the chiral smectic C (S C) formation and chiral SC* stabilization, and it simultaneously causes the liquid crystal temperature range of chiral S C* to be broader. The siloxane member is helpful in reducing the smectic C (SC) transation shift temperature, and the molecule containing tris-siloxane units shows better effect than the bis-siloxane one. The synthesis and characterization of the new FLCs materials which exhibit SC* phase at room temperature and higher spontaneous polarization are presented.
- Lin, Chih-Hung
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experimental part
p. 33 - 42
(2012/05/04)
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- Asymmetric synthesis of (+)-aspicilin
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Aspicilin (1), an eighteen membered macrolide with four stereocenters, was synthesized using (3R,4R)- 1,5-hexadiene-3,4-diol and (S)-propylene oxide as the starting materials. Sharpless epoxidation on the protected dienediol generated the required three c
- Wang, Chun-Yi,Hou, Duen-Ren
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scheme or table
p. 389 - 393
(2012/08/08)
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- Syntheses and palladium, platinum, and borane adducts of symmetrical trialkylphosphines with three terminal vinyl groups, P((CH2) mCH=CH2)3
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Reactions of Br(CH2)mCH=CH2 with Mg powder and then PCl3 (0.33 equiv.) afford P((CH2)m-CH=CH 2)3 (1; m = a, 4; b, 5; c, 6; d, 7; e, 8; f, 9; 52-87 %). Reactions of 1a-c, e with PdX2(COD) (X = Cl, Br) give trans-PdX 2(P((CH2)mCH=CH2)3) 2 (35-92 %). Reactions of 1b-e with PtCl2 in benzene give mainly trans-PtCl2(P((CH2)mCH=CH 2)3)2 (trans-5b-e; 52-75 %), whereas those with K2PtCl4 in water give mainly cis-5b-e (33-70 %). The reaction of equimolar quantities of 1c and H3B.S(CH3) 2 gives the 1 : 1 adduct H3B·P((CH 2)6CH=CH2)3 (85 %). In none of these transformations are by-products derived from the C=C linkages observed.
- Nawara-Hultzsch, Agnieszka J.,Skopek, Katrin,Shima, Takanori,Barbasiewicz, Micha,Hess, Gisela D.,Skaper, Dirk,Gladysz, John A.
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body text
p. 414 - 424
(2010/10/01)
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- Evaluation of exo-endo ratios in the halolactonization of ω-unsaturated acids
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The reaction of 2-(ω-alkenyl)benzoic acids with bis(collidine)iodine and bis(collidine)bromine hexafluorophosphate was examined. Except with 2-but-3-enylbenzoic acid, for which only the exo lactone was obtained, for the other acids a mixture of exo-endo lactones was always obtained. The proportion of endo lactone was important for the acid chain length of 11 carbons (formation of a 12-membered ring endo lactone) and for the acid chain lengths higher than 14 carbons. The formation of the endo lactones was explained, on the base of molecular calculations, by competition between electronic and steric effects. These latter were developed by transannular interactions (for the acid chain lengths 8-11) and/or the conformations adopted by the chains (for the acid chain lengths ≥ 14,) which disfavored the formation of the exo lactones. The larger proportion of endo lactones observed with the bromo reagent compared to the iodo reagent seemed due to electronic factors.
- Roux,Paugam,Rousseau
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p. 4304 - 4310
(2007/10/03)
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- Efficient synthesis of 40- and 48-membered tetraether macrocyclic bisphosphocholines.
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An efficient route toward the synthesis of unsaturated (bis-diacetylenic) and saturated 40- and 48-membered macrocyclic biphosphocholines has been developed using 2-phenyl-5-hydroxy-1,3-dioxane as a common glycerol synthon. Ring closure was accomplished using either high-dilution Glaser oxidation of [(Cy3P)2RU==CHPh]Cl2-catalyzed olefin metathesis conditions. Deprotection of benzyl ethers using trimethylsilyl iodide (TMS-I) in the presence of diacetylenic moieties has also been demonstrated for the first time.
- Patwardhan,Thompson
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p. 241 - 243
(2008/02/13)
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- Dilithium tetrachlorocuprate catalyzed coupling of allylmagnesium bromide with α,ω-dihaloalkanes
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Allylmagnesium bromide has been shown to cross-couple with α,ω- dihaloalkanes in the presence of dilithium tetrachlorocuprate to yield, depending on reaction conditions, mono-coupled haloalkenes or di-coupled alkadienes. The order of the reactivity of the dihalides is I > Br >> CI and secondary halides show greater reactivity than primary halides.
- Johnson,Donohoe,Kang
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p. 1557 - 1564
(2007/10/02)
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- First Synthesis of the Cytotoxic and Antifungal C14-Amine (2S,3E,5Z)-2-Amino-3,5,13-tetradecatriene Isolated from the New Zealand Ascidian Pseudodistoma novaezelandiae
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The synthesis of (2S,3E,5Z)-2-amino-3,5,13-tetradecatriene with high enantiomeric purity in excellent overall yield is described.In the crucial step the stereogenic center was generated by nucleophilic addition of tert-butyl carbamate to a planar-chiral tetracarbonyliron(1+) complex. Key Words: (2S,3R,5Z)-2-Amino-3,5,13-tetradecatriene / Cytotoxic agents / Antifungal agents / Amination / Iron-mediated allylic amination / Pseudodistoma novaezelandiae
- Enders, Dieter,Finkam, Michael
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p. 551 - 556
(2007/10/02)
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