18417-00-0Relevant academic research and scientific papers
Chirality-controlled syntheses of double-helical Au nanowires
Nakagawa, Makoto,Kawai, Takeshi
supporting information, p. 4991 - 4994 (2018/04/24)
The selective large-scale syntheses of noble metal nanocrystals with complex shapes using wet-chemical approaches remain exciting challenges. Here we report the chirality-controllable syntheses of double-helical Au nanowires (NWs) using chiral soft-templates composed of two organogelators with their own active functions; one organogelator serves to introduce helicity into the template and the other acts as a capping agent to control the Au shape. One-dimensional twisted-nanoribbon templates are prepared simply by mixing the two organogelators in water containing a small amount of toluene, followed by the addition of LiCl; template chirality is controlled through the selection of the handedness of the helicity-inducing organogelator. Double-helical Au NWs synthesized on these chiral templates have the same helical structure as the template because the Au NWs grow along both edges of the twisted nanoribbons with right- or left-handed helicities. Dispersions of the right- and left-handed double-helical Au NWs exhibit opposite CD signals.
Cyclic fatty acyl glycosides in the glandular trichome exudate of Silene gallica
Asai, Teigo,Fujimoto, Yoshinori
experimental part, p. 1410 - 1417 (2011/04/25)
Chemical investigation of the glandular trichome exudate from Silene gallica L. (Caryophyllaceae) resulted in isolation of 10 cyclic fatty acyl glycosides (gallicasides A-J). The cyclic structures were characterized by a glycosidic linkage of the glucose moiety to either the C-12 or the C-13 position of the octadecanoyl moiety, and by an ester linkage between the C-2 hydroxy group of the glucose moiety and the carboxyl group of the oxygenated octadecanoic acid. The structures of the cyclic fatty acyl glycosides were further distinguished from one another by acetylation and/or malonylation on the glucose moiety. Of these compounds, the 1,2′-cyclic ester of 12(R)-(6-O-acetyl-3-O-malonyl-β-d-glucopyranosyloxy)octadecanoic acid (gallicaside J) was the most abundant (30.7%). These secondary metabolites were found specifically in the glandular trichome exudate rather than in other aerial parts.
Efficient and flexible synthesis of chiral γ- And δ-lactones
Habel, Andreas,Boland, Wilhelm
supporting information; experimental part, p. 1601 - 1604 (2008/10/09)
An efficient and highly flexible synthesis for chiral γ- and δ-lactones with high enantiomeric purity is described (>99% ee and 57-87% overall yield). The protocol involves alkylation of chiral 1,2-oxiranes with terminally unsaturated Grignard reagents. Subsequent oxidative degradation (OsO4-Oxone) of the terminal double bond from chiral alk-1-en-5-ols and alk-1-en-6-ols affords 4- or 5-hydroxy acids and γ- and δ-lactones after acidic workup. The flexibility and efficiency of the protocol is illustrated by the synthesis of several alkanolides and alkenolides, hydroxy fatty acids and dihydroisocoumarins. The Royal Society of Chemistry 2008.
Electroorganic synthesis 65. Anodic homocoupling of carboxylic acids derived from fatty acids
Weiper-Idelmann, Andreas,Aus Dem Kahmen, Martin,Schaefer, Hans J.,Gockeln, Marianne
, p. 672 - 682 (2007/10/03)
Fatty acid derived carboxylic acids with double bonds, hydroxy-, amino-, keto-, ester- and epoxy groups are anodically coupled to dimers (Kolbe electrolysis) in 29 to 81% yield and up to a 2.5 mol scale. Problems due to the low conductivity of fatty acid salts were overcome by the use of a flow cell with a narrow electrode gap. Fatty acids with branched alkyl chains gave dimers with interesting emulsifying properties. Dimethyl hexadecanedioate, accessible from methyl azelate, could be cyclized and further converted into homomuscone and muscone in a few steps. A commercial mixture of dimeric fatty acids (C36-dicarboxylic acids) has been coupled to give C70-diesters. Acta Chemica Scandinavica 1998. Part 64: Nielsen, M. F., Batanero, B.,.
Properties of unusual phospholipids. III: Synthesis, monolayer investigations and DSC studies of hydroxy octadeca(e)noic acids and diacylglycerophosphocholines derived therefrom
Negelmann, Lars,Pisch, Sandra,Bornscheuer, Uwe,Schmid, Rolf D.
, p. 117 - 134 (2007/10/03)
Diacylglycerophosphocholines containing (R)-3-, (R)-12-, (R)-17-hydroxy octadeca(e)noic acids and the corresponding racemates were synthesized and purified to homogeneity. The influence of the position of the hydroxy group on the monolayer packing properties of these fatty acids and their phosphatidylcholines was studied by Langmuir techniques and 1,2-di-[(R)-12-hydroxy-octadec-cis-9-enyl]-sn-glycero-3-phosphocholine displayed the largest lift-off area (330 A2/molecule). This result was in line with the thermotropic phase behavior of these phospholipids, as measured by differential scanning calorimetry (DSC): the gel- to liquid-crystalline phase transition temperature (T(m))passed through a minimum of -15.1°C for 1,2-di-[(R)-12-hydroxy-octadec-cis-9-enyl]-sn-glycero-3-phosphocholine.
An Asymmetric Synthesis of Acyclic and Macrocyclic α-Alkyl Ketones. The Role of (E)- and (Z)-Lithioenamines
Meyers, A. I.,Williams, Donald R.,White, Steven,Erickson, Gary W.
, p. 3088 - 3093 (2007/10/02)
Metalation and alkylation of chiral imines derived from C10, C12, and C15 cyclic ketones gave, under kinetic metalation conditions, 2-alkylcycloalkanones of absolute configuration opposite to that formed from thermodynamic metalation.Thus, (S)-(-)-2-methylcyclododecanone is formed kinetically in 60percent ee, whereas (R)-(+)-methylcyclododecanone is reached in 80percent ee under thermodynamic conditions.In a similar fashion, acyclic ketones 20, via their chiral imines 17, are alkylated enantioselectively under both kinetic and thermodynamic modes.The kinetic metalation gives exclusively the (Z)-lithioenamines (19), while reflux of this lithio anion gives only the (E)-lithioenamine (19).Chiral α-substituted ketones are produced in 18-97percent ee.
