2695-48-9Relevant articles and documents
'Chiron' approach to the total synthesis of macrolide (+)-Aspicilin
Saidhareddy, Puli,Ajay, Sama,Shaw, Arun K.
, p. 4253 - 4259 (2014)
An efficient total synthesis of 18 membered macrolactone, (+)-Aspicilin (lichen macrolide) has been achieved in 12 linear steps with 10.2% overall yield from carbohydrate based building block d-glucal. Highlights of the strategy include preparation of 2-deoxysugar from protected glycal 14, two-carbon Wittig olefination of the Swern oxidised intermediate 7, union of 'carbohydrate based' fragment 5 and a long chain (C-11) chiral alcohol 6 by Yamaguchi esterification and finally ring closing metathesis of the resulting compound 4.
Double bond-containing fullerene liquid crystal compound and application thereof
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Paragraph 0045-0049, (2020/10/19)
The invention discloses a fullerene liquid crystal compound which has a high refractive index and contains double-bond functional groups, a preparation method of the liquid crystal compound, and an application of the liquid crystal compound serving as a filling material in the field of photonic crystals. The fullerene liquid crystal molecular structure is composed of three parts, namely a rigid fullerene acid part, a flexible double bond-containing gallic acid derivative part, and a flexible chain segment part connecting the rigid fullerene acid part and the flexible double-bond-containing gallic acid derivative part; the precursor of the flexible chain segment is diol; and two ends of the flexible chain segment are respectively connected with the fullerene acid part and the double bond-containing gallic acid derivative part through ester bonds. The fullerene liquid crystal compound has high refractive index, so that the compound can well replace a liquid crystal molecule with low refractive index to serve as the filling material of the photonic crystal, and the photonic crystal with high refractive index contrast ratio and excellent performance is obtained.
Synthesis and characterization of some atypical sphingoid bases
Saied, Essa M.,Le, Thuy Linh-Stella,Hornemann,Arenz, Christoph
supporting information, p. 4047 - 4057 (2018/06/30)
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.
Long-Chain Alkyl Cyanides: Unprecedented Volatile Compounds Released by Pseudomonas and Micromonospora Bacteria
Montes Vidal, Diogo,von Rymon-Lipinski, Anna-Lena,Ravella, Srinivasa,Groenhagen, Ulrike,Herrmann, Jennifer,Zaburannyi, Nestor,Zarbin, Paulo H. G.,Varadarajan, Adithi R.,Ahrens, Christian H.,Weisskopf, Laure,Müller, Rolf,Schulz, Stefan
supporting information, p. 4342 - 4346 (2017/04/03)
The analysis of volatiles from bacterial cultures revealed long-chain aliphatic nitriles, a new class of natural products. Such nitriles are produced by both Gram-positive Micromonospora echinospora and Gram-negative Pseudomonas veronii bacteria, although the structures differ. A variable sequence of chain elongation and dehydration in the fatty acid biosynthesis leads to either unbranched saturated or unsaturated nitriles with an ω?7 double bond, such as (Z)-11-octadecenenitrile, or methyl-branched unsaturated nitriles with the double bond located at C-3, such as (Z)-13-methyltetradec-3-enenitrile. The nitrile biosynthesis starts from fatty acids, which are converted into their amides and finally dehydrated. The structures and biosyntheses of the 19 naturally occurring compounds were elucidated by mass spectrometry, synthesis, and feeding experiments with deuterium-labeled precursors. Some of the nitriles showed antimicrobial activity, for example, against multiresistant Staphylococcus aureus strains.
PROCESS INVOLVING CROSS METATHESIS OF OLEFINS
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Page/Page column 26, (2015/10/05)
A method of forming a macrocyclic musk compound comprising the steps of:- i) cross-metathesizing a first olefin and a second olefin in the presence of a homogeneous transition metal catalyst comprising an alkylidene ligand, to form a statistical mixture of a hetero-dimer intermediate of said first and second terminal olefin, and homo-dimers ii) separating the hetero-dimer from the statistical mixture of hetero-and homo- dimers iii) and cyclizing the hetero-dimer intermediate to form the macrocyclic musk compound.
ADMET Polymers Containing Precisely Spaced Pendant Boronic Acids and Esters
Simocko, Chester,Young, Thomas C.,Wagener, Kenneth B.
, p. 5470 - 5473 (2015/09/02)
Precise aryl boronic ester- and acid-containing polymers have been synthesized via acyclic diene metathesis. High-molecular weight phenyl boronic acid polymers were synthesized. Cross-linked phenyl boronic acid polymers were also synthesized and demonstrate a unique crystallization behavior not usually seen in cross-linked polymers. (Graph Presented).
Low catalyst loading in ring-closing metathesis reactions
Kadyrov, Renat
supporting information, p. 1002 - 1012 (2013/02/23)
An efficient procedure is described for ring-closing metathesis reactions. A conversion of 95 % for diethyl diallylmalonate in dilute solution could be achieved within a few minutes, reaching TOF=4173min-1, with very low loading of commercially available Ru catalysts that contained unsaturated NHC ligands. In general, only 50 to 250ppm of the catalyst is required to achieve near-quantitative conversion into a broad variety of 5-16-membered heterocyclic compounds. The practicality of this procedure was illustrated in the synthesis of 5-8-membered N-tert-butoxycarbonyl (N-Boc)- and N-para-toluenesulfonyl (N-Ts)-protected cyclic amines and 9-16-membered lactones. The synthesis of macrocyclic proline-based lactams required slightly higher catalyst loadings. Along with monocyclic products, oligomeric byproducts, mostly cyclodimers, were isolated and characterized. Getting some closure: An efficient procedure is described for ring-closing metathesis reactions in which only 50 to 250ppm of catalyst is required to effect almost-quantitative conversion into a broad range of 5-16-membered heterocyclic compounds. The practicality of this procedure was illustrated in the synthesis of 5-8-membered N-protected cyclic amines, 9-16-membered lactones, and 11-16-membered proline-based lactams. Copyright
Syntheses and palladium, platinum, and borane adducts of symmetrical trialkylphosphines with three terminal vinyl groups, P((CH2) mCH=CH2)3
Nawara-Hultzsch, Agnieszka J.,Skopek, Katrin,Shima, Takanori,Barbasiewicz, Micha,Hess, Gisela D.,Skaper, Dirk,Gladysz, John A.
body text, p. 414 - 424 (2010/10/01)
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.
Alkenylsilane structure effects on mononuclear and binuclear organotitanium-mediated ethylene polymerization: Scope and mechanism of simultaneous polyolefin branch and functional group introduction
Amin, Smruti B.,Marks, Tobin J.
, p. 2938 - 2953 (2007/10/03)
Alkenylsilanes of varying chain lengths are investigated as simultaneous chain-transfer agents and comonomers in organotitanium-mediated olefin polymerization processes. Ethylene polymerizations were carried out with activated CGCTiMe2 and EBICGCTi2Me4 (CGC = Me2Si(Me4C5)(NtBu); EBICGC = (μ-CH2CH2-3,3′){(η5-indenyl)[1- Me2Si(tBuN)]}2) precatalysts in the presence of allylsilane, 3-butenylsilane, 5-hexenylsilane, and 7-octenylsilane. In the presence of these alkenylsilanes, high polymerization activities (up to 10 7 g of polymer/(mol of Ti-atm ethylene·h)), narrow product copolymer polydispersities, and substantial amounts of long-chain branching are observed. Regardless of Ti nuclearity, alkenylsilane incorporation levels follow the trend C8H15SiH3 6H 11SiH3 ≈ C4H7SiH3 3H5SiH3. Alkenylsilane comonomer incorporation levels are consistently higher for CGCTiMe2-mediated copolymerizations (up to 54%) in comparison with EBICGCTi2Me 4-mediated copolymerizations (up to 32%). The long-chain branching levels as compared to the total branch content follow the trend C 3H5SiH3 4H7SiH 3 ≈ C6H11SiH3 ≈ C 8H15SiH3, with gel permeation chromatography-multi-angle laser light scattering-derived branching ratios (gM) approaching 1.0 for C8H15SiH3. Time-dependent experiments indicate a linear increase of copolymer Mw with increasing polymerization reaction time. This process for producing long-chain branched polyolefins by coupling of an α-olefin with a chain-transfer agent in one comonomer is unprecedented. Under the conditions investigated, alkenylsilanes ranging from C3 to C8 are all efficient chain-transfer agents. Ti nuclearity significantly influences silanolytic chain-transfer processes, with the binuclear system exhibiting a sublinear relationship between Mn and [alkenylsilane]-1 for allylsilane and 3-butenylsilane, and a superlinear relationship between Mn and [alkenylsilane]-1 for 5-hexenylsilane and 7-octenylsilane. For the mononuclear Ti system, alkenylsilanes up to C 6 exhibit a linear relationship between Mn and [alkenylsilane]-1, consistent with a simple silanolytic chain termination mechanism.
The first total synthesis of naturally occurring (+)-gymnasterkoreayne F and its enantiomer
Carpita, Adriano,Braconi, Silvia,Rossi, Renzo
, p. 2501 - 2508 (2007/10/03)
The first total synthesis of naturally occurring (+)-gymnasterkoreayne F and its enantiomer is reported. The seven-step route to these two polyacetylenes in enantiomerically pure form involves the use of (+)-2,3-O-isopropylidene-l- threitol and (-)-2,3-O-isopropylidene-d-threitol, respectively, as the starting material and a Cadiot-Chodkiewicz reaction as a key step. The absolute configuration of (+)-gymnasterkoreayne F has been confirmed to be (2E,8S,Z). The natural product and its enantiomer have been found to exhibit modest cytotoxicity against the 60 human tumor cell lines of the National Cancer Institute.
