42890-76-6Relevant articles and documents
Blasticidin A as an inhibitor of aflatoxin production by Aspergillus parasiticus
Sakuda,Ono,Ikeda,Nakamura,Inagaki,Kawachi,Nakayama,Suzuki,Isogai,Nagasawa
, p. 1265 - 1271 (2000)
Blasticidin A, an antibiotic, showed strong inhibitory activity toward aflatoxin production by Aspergillus parasiticus. Its structure was characterized by NMR and chemical degradation experiments as 1, which is a tetramic acid derivative with a highly oxygenated long alkyl chain similar to aflastatin A (2). Absolute configurations of the eight chiral centers at C-4, 6, 31, 32, 33, 34, 35 and 37 of 1 were chemically determined. Blasticidin A almost completely inhibited aflatoxin production at 0.5 μm.
Development of an Efficient Process for the Decomposition of the Borate Complexes Formed during the Large-Scale Synthesis of (S)-1,2,4-Butanetriol
Liu, Qian,Xiong, Fang-Jun,He, Qiu-Qin,Chen, Fen-Er
, p. 1540 - 1542 (2013)
An improved multikilogram-scale process for the production of (S)-1,2,4-butanetriol has been developed. This process involves the efficient removal of residual boric acid and the decomposition of the borate complexes formed during the reduction of (-)-dimethyl malate with sodium borohydride by methanolysis using a circular distillation-coupled hydrolysis apparatus.
EXPERIMENTAL AND THEORETICAL STUDY OF THE STRUCTURES AND OPTICAL ROTATIONS OF CHIRAL BICYCLIC ORTHO ESTERS.
Wroblewski,Applequist,Takaya,Honzatko,Kim,Jacobson,Reitsma,Yeung,Verkade
, p. 4144 - 4150 (1988)
The approach adopted in this study was to determine the structure of a single crystal of a pure enantiomer of one of the ortho esters by X-ray diffraction and then to utilize the coordinates so found for the bicyclic moiety in calculating the optical rotations of the remaining members of the series. Because of the high sensitivity of the calculated rotations to the atomic coordinates, this approach is subject to the experimental uncertainties inherent in the X-ray diffraction technique. Thus, we explore here some restrained refinement procedures to reduce the effect of these uncertainties on the calculated molar rotations. Study shows that the dipole interaction theory accomplishes this for the esters though it also reveals a potential hazard in establishing this connection for molecules wherein interactions of high order among atoms are significant.
Optically active isonitrile ligand for palladium-catalyzed enantioselective bis-silylation of carbon-carbon double bonds
Suginome, Michinori,Nakamura, Hiroshi,Ito, Yoshihiko
, p. 555 - 558 (1997)
Intramolecular bis-silylation of homoallylic alcohols proceeded enantioselectively in the presence of a catalyst prepared from Pd(acac), and optically active isonitriles, derived from a common chiral source, (+)-ketopinic acid.
Biochemistry-Guided Prediction of the Absolute Configuration of Fungal Reduced Polyketides
Akimitsu, Kazuya,Guo, Yian,Hashimoto, Masaru,Kotani, Akari,Minami, Atsushi,Mochizuki, Susumu,Oikawa, Hideaki,Ozaki, Taro,Peng, Wenquan,Takino, Junya,Ye, Tao,Yu, Jie
supporting information, p. 23403 - 23411 (2021/09/18)
Highly reducing polyketide synthases (HR-PKSs) produce structurally diverse polyketides (PKs). The PK diversity is constructed by a variety of factors, including the β-keto processing, chain length, methylation pattern, and relative and absolute configurations of the substituents. We examined the stereochemical course of the PK processing for the synthesis of polyhydroxy PKs such as phialotides, phomenoic acid, and ACR-toxin. Heterologous expression of a HR-PKS gene, a trans-acting enoylreductase gene, and a truncated non-ribosomal peptide synthetase gene resulted in the formation of a linear PK with multiple stereogenic centers. The absolute configurations of the stereogenic centers were determined by chemical degradation followed by comparison of the degradation products with synthetic standards. A stereochemical rule was proposed to explain the absolute configurations of other reduced PKs and highlights an error in the absolute configurations of a reported structure. The present work demonstrates that focused functional analysis of functionally related HR-PKSs leads to a better understanding of the stereochemical course.
IMMUNOMODULATORY GLYCOSPHINGOLIPIDS AND METHODS OF USE THEREOF
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Page/Page column 41; 43, (2020/08/28)
Provided herein are a subset of alpha-galactosylceramide (alpha-GC) compounds having improved immunomodulatory activity, particularly with respect to NKT cell number and activity. Also provided herein are methods of use of such compounds, including in the modulation of NKT cells and/or activity in vivo. Further provided are combinatorial synthesis methods for generating alpha-GC compounds of specifically defined structure and thereby generating pure preparations thereof.
Preparation method of (S)-1, 2, 4-butantriol[7]
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Paragraph 0034; 0040-0043; 0049-0050, (2020/05/05)
The invention relates to a preparation method of (S)-1, 2, 4-butantriol, which comprises the following steps: reacting (S)-benzyloxymethyl ethylene oxide with a magnesium halide Grignard reagent of benzyl halomethyl ether to obtain (S)-1, 4-dibenzyloxy-2-butanol; and under the action of a palladium-carbon catalyst, hydrogenating to remove a benzyl protecting group to obtain a final product. The method is short in synthetic route, less in three wastes and suitable for industrial production.
Synthesis of a C1-C12 Fragment of Gulmirecin B
Maier, Martin E.,Rengarasu, Rathikrishnan
supporting information, p. 1346 - 1350 (2019/06/20)
The synthesis of a C1-C14 fragment of the macrolide antibiotic gulmirecin B through formation of the C7-C8 bond by addition of a vinyllithium intermediate to a C1-C7 aldehyde was investigated. This crucial coupling was successful with a vinyllithium reagent corresponding to a C8-C12 fragment. The C8-C12 vinyl bromide was prepared from l -malic acid. The C1-C7 aldehyde building block was synthesized from hex-5-enoic acid by using an Evans alkylation, a cross-metathesis, and an asymmetric dihydroxylation as key steps.
A S - (+) -3 - hydroxy tetrahydrofuran chemical synthesis method
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Paragraph 0020-0022, (2019/04/04)
The invention discloses a S - (+) - 3 - hydroxy tetrahydrofuran chemical synthesis method, includes the following operation steps: 1, compound 1 in the presence of thionyl chloride and methanol reaction to obtain compound 2; 2, in the solvent, compound 2 in the presence of a reducing agent and the reaction to obtain compound 3; 3, compound 3 in the presence of paratoluene sulfonic acid, reaction to obtain compound S - (+) - 3 - hydroxy tetrahydrofuran.
Stabilization of NaBH4 in Methanol Using a Catalytic Amount of NaOMe. Reduction of Esters and Lactones at Room Temperature without Solvent-Induced Loss of Hydride
Prasanth,Joseph, Ebbin,Abhijith,Nair,Ibnusaud, Ibrahim,Raskatov, Jevgenij,Singaram, Bakthan
, p. 1431 - 1440 (2018/02/09)
Rapid reaction of NaBH4 with MeOH precludes its use as a solvent for large-scale ester reductions. We have now learned that a catalytic amount of NaOMe (5 mol %) stabilizes NaBH4 solutions in methanol at 25 °C and permits the use of these solutions for the reduction of esters to alcohols. The generality of this reduction method was demonstrated using 22 esters including esters of naturally occurring chiral γ-butyrolactone containing dicarboxylic acids. This method permits the chemoselective reductions of esters in the presence of cyano and nitro groups and the reductive cyclization of a pyrrolidinedione ester to a fused five-membered furo[2,3-b]pyrrole and a (-)-crispine A analogue in high optical and chemical yields. Lactones, aliphatic esters, aromatic esters containing electron-withdrawing groups, and heteroaryl esters are reduced more rapidly than aryl esters containing electron-donating groups. The 11B NMR spectrum of the NaOMe-stabilized NaBH4 solutions showed a minor quartet due to monomethoxyborohydride (NaBH3OMe) that persisted up to 18 h at 25 °C. We postulate that NaBH3OMe is probably the active reducing agent. In support of this hypothesis, the activation barrier for hydride transfer from BH3(OMe)- onto benzoic acid methyl ester was calculated as 18.3 kcal/mol.