534-00-9Relevant academic research and scientific papers
Effect of regioregularity and role of heteroatom on the chiral behavior of oligo(heteroalkyl thiophene)s
Marinelli, Martina,Angiolini, Luigi,Lanzi, Massimiliano,Di Maria, Francesca,Salatelli, Elisabetta
supporting information, p. 1361 - 1376 (2020/11/23)
Novel optically active oligothiophenes bearing electron-donating chiral side chains have been prepared by synthetic methods suitable to achieve regioregular head-to-tail and head-to-head/tail-to-tail derivatives. In particular, the chiral (S)-(2-methyl)butyl moiety was linked at position 3 of the thiophene ring through heteroatoms, such as S or O, to evaluate its effect on the macro molecular aggregation and, consequently, on the chiroptical properties of the material in the solid state. The materials have been fully characterized and investigated by optical and chiroptical methods upon aggregation both from the solution and as cast films. Compared with the related head-to-tail and head-to-head/tail-to-tail poly(3-alkyl)thiophene derivatives, with the same optically active moiety directly linked to the ring and possessing a higher polymerization degree, the chiroptical properties of the newly synthesized oligomers were significant, or even better, and provided insight into the role of intrachain–interchain interactions between the heteroatom and the thienyl sulfur atom.
Synthesis and mass spectra of rearrangement bio-signature metabolites of anaerobic alkane degradation via fumarate addition
Chen, Jing,Zhou, Lei,Liu, Yi-Fan,Hou, Zhao-Wei,Li, Wei,Mbadinga, Serge Maurice,Zhou, Jing,Yang, Tao,Liu, Jin-Feng,Yang, Shi-Zhong,Wu, Xiao-Lin,Gu, Ji-Dong,Mu, Bo-Zhong
, (2020/05/01)
Metabolite profiling in anaerobic alkane biodegradation plays an important role in revealing activation mechanisms. Apart from alkylsuccinates, which are considered to be the usual biomarkers via fumarate addition, the downstream metabolites of C-skeleton rearrangement can also be regarded as biomarkers. However, it is difficult to detect intermediate metabolites in both environmental samples and enrichment cultures, resulting in lacking direct evidence to prove the occurrence of fumarate addition pathway. In this work, a synthetic method of rearrangement metabolites was established. Four compounds, namely, propylmalonic acid, 2-(2-methylbutyl)malonic acid, 2-(2-methylpentyl)malonic acid and 2-(2-methyloctyl)malonic acid, were synthesized and determined by four derivatization approaches. Besides, their mass spectra were obtained. Four characteristic ions were observed at m/z 133 + 14n, 160 + 28n, 173 + 28n and [M - (45 + 14n)]+ (n = 0 and 2 for ethyl and n-butyl esters, respectively). For methyl esterification, mass spectral features were m/z 132, 145 and [M - 31]+, while for silylation, fragments were m/z 73, 147, 217, 248, 261 and [M - 15]+. These data provide basis on identification of potential rearrangement metabolites in anaerobic alkane biodegradation via fumarate addition.
Yakushinamides, Polyoxygenated Fatty Acid Amides That Inhibit HDACs and SIRTs, from the Marine Sponge Theonella swinhoei
Takada, Kentaro,Imae, Yasufumi,Ise, Yuji,Ohtsuka, Susumu,Ito, Akihiro,Okada, Shigeru,Yoshida, Minoru,Matsunaga, Shigeki
, p. 2384 - 2390 (2016/10/04)
Yakushinamides A (1) and B (2), prolyl amides of polyoxygenated fatty acids, have been isolated from the marine sponge Theonella swinhoei as inhibitors of HDACs and SIRTs. Their planar structures were determined by interpretation of the NMR data of the intact molecules and tandem FABMS data of the methanolysis products. For the assignment of the relative configurations of the three contiguous oxymethine carbons in 1 and 2, Kishi's universal NMR database was applied to the methanolysis products. During the assignments of relative configurations of the isolated 1-hydroxy-3-methyl moiety in 1 and the isolated 1-hydroxy-2-methyl moiety in 2, we found diagnostic NMR features to distinguish each pair of diastereomers. The absolute configurations of 1 and 2 were determined by a combination of the modified Mosher's method and Marfey's method. Although the modified Mosher's method was successfully applied to the methanolysis product of 1, this method gave an ambiguous result at C-20 when applied to the methanolysis product of 2, even after oxidative cleavage of the C-14 and C-15 bond.
Straightforward synthesis of all stenusine and norstenusine stereoisomers
Mueller, Tobias,Dettner, Konrad,Seifert, Karlheinz
experimental part, p. 6032 - 6038 (2011/12/15)
All the stereoisomers of stenusine (1) and norstenusine (21) have been efficiently synthesized by the asymmetric hydrogenation of pyridines. The (2R,3S)- and (2R,3R)-isomers of 1, that are difficult to prepare, have been synthesized for the first time using a chemoenzymatic approach in eight steps with an 8 % total yield. All the target compounds were obtained in good stereochemical purity by using very simple and inexpensive reagents and auxiliaries. All the stereoisomers of the defensive alkaloids stenusine and norstenusine produced by Stenus beetles have been synthesized in a straightforward manner. The chiral (S) side chain is derived from (S)-2-methyl-1-butanol. For the difficult preparation of (R)-3-(2-methylbutyl) pyridine, a highly efficient chemoenzymatic approach was developed.
Pheromone synthesis. Part 243: Synthesis and biological evaluation of (3R,13R,1′S)-1′-ethyl-2′-methylpropyl 3,13-dimethylpentadecanoate, the major component of the sex pheromone of Paulownia bagworm, Clania variegata, and its stereoisomers
Mori, Kenji,Tashiro, Takuya,Zhao, Boguang,Suckling, David M.,El-Sayed, Ashraf M.
experimental part, p. 2642 - 2653 (2010/05/18)
All of the four stereoisomers of (1′S)-1′-ethyl-2′-methylpropyl 3,13-dimethylpentadecanoate, the major component of the female sex pheromone of Clania variegata, were synthesized by employing olefin cross metathesis as the key reaction and starting from (R)- or (S)-2-methyl-1-butanol, (R)- or (S)-citronellal, and (S)-2-methyl-3-pentanol. Their bioassay revealed the (3R,13R,1′S)-isomer as the bioactive one, whose more efficient synthesis was achieved in two different ways by employing Wittig reaction as the key step.
New syntheses of 1,7-dimethylnonyl propanoate, the western corn rootworm pheromone, in four different ways via cross metathesis, alkylation and coupling reactionsss
Mori, Kenji
experimental part, p. 595 - 600 (2011/04/23)
A mixture of the four stereoisomers of 1,7-dimethylnonyl propanoate, the female sex pheromone of the western corn rootworm (Diabrotica virgifera virgifera LeConte), was synthesized in four different ways by employing one of the following four reactions as the key step: (i) cross metathesis using the Grubbs I catalyst, (ii) cross metathesis using the Grubbs II catalyst, (iii) alkylation of an alkynide anion, and (iv) Grignard coupling in the presence of dilithium tetrachlorocuprate. Although the cross metathesis approaches enabled two short syntheses (4 or 6 steps) of the pheromone to be achieved, the cheapest and most efficient synthesis was possible via Grignard coupling to give the desired pheromone in a 40% overall yield based on 2-methyl-1-butanol (8 steps).
Synthesis of all the four stereoisomers of (1′S)-1-ethyl-2-methylpropyl 3,13-dimethylpentadecanoate, the major component of the sex pheromone of Paulownia bagworm, Clania variegata
Mori, Kenji,Tashiro, Takuya
scheme or table, p. 3266 - 3269 (2009/09/05)
All the four stereoisomers of (1′S)-1-ethyl-2-methylpropyl 3,13-dimethylpentadecanoate, the major component of the sex pheromone of Clania variegata, were synthesized by starting from (R)- or (S)-2-methylbutan-1-ol, (R)- or (S)-citronellal, and (S)-2-methylpentan-3-ol. Olefin cross metathesis was employed as the key reaction.
Pheromone synthesis. Part 240: Cross-metathesis with Grubbs I (but not Grubbs II) catalyst for the synthesis of (R)-trogodermal (14-methyl-8-hexadecenal) to study the optical rotatory powers of compounds with a terminal sec-butyl group
Mori, Kenji
experimental part, p. 3900 - 3909 (2009/09/08)
(R)-Trogodermal (14-methyl-8-hexadecenal), the sex pheromone of Trogoderma species of pest insects against stored products, and its (S)-isomer were synthesized by using olefin cross-metathesis between (R)- or (S)-7-methyl-1-nonene and 8-nonenyl acetate as the key step. This step was successful with Grubbs I but not with Grubbs II catalyst. The latter caused randomization of the carbon skeleton to give a mixture of abnormal products with both longer or shorter carbon chains than the desired product. The specific rotations of 18 newly and 6 previously synthesized compounds with a terminal sec-butyl group were measured to conclude them to be [α]D +3.5 to +6.5 or -3.6 to -6.4.
Photochromic glassy liquid crystals comprising mesogenic pendants to dithienylethene cores
Kim, Chunki,Marshall, Kenneth L.,Wallace, Jason U.,Chen, Shaw H.
supporting information; experimental part, p. 5592 - 5598 (2010/03/03)
Photochromic glassy liquid crystals were synthesized using dithienylethenes as the volume-excluding cores to which liquid crystalline mesogens were chemically bonded through alkyl spacers. Nematic, smectic, and cholesteric glassy liquid crystals were demonstrated with glass transition temperatures above 90 °C and clearing points up to 220 °C without traces of crystallization on cooling or crystalline melting on heating. A monodomain cholesteric glassy liquid crystalline film containing an enantiomeric 2-methylpropylene chiral spacer was characterized as a left-handed helical stack, exhibiting a selective reflection band centered at 686 nm, an orientational order parameter of 0.65 for the quasi-nematic layers, and a combination of reflective coloration with photoswitchable absorptive coloration.
First total synthesis and assignment of the absolute configuration of the neuronal cell protecting alkaloid carbazomadurin B
Kn?ll, Jan,Kn?lker, Hans-Joachim
, p. 651 - 653 (2007/10/03)
Using a palladium-catalyzed approach, the first enantio-selective synthesis of the neuronal cell protecting agent carbazomadurin B is described and its absolute configuration is assigned. Georg Thieme Verlag Stuttgart.
