- PROCESS FOR THE PREPARATION OF ORGANIC BROMIDES
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The present invention provides a process for the preparation of organic bromides, by a radical bromodecarboxylation of carboxylic acids with a bromoisocyanurate.
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Paragraph 00169; 00172; 00173
(2017/07/28)
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- Tuning the Diiron Core Geometry in Carboxylate-Bridged Macrocyclic Model Complexes Affects Their Redox Properties and Supports Oxidation Chemistry
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We introduce a novel platform to mimic the coordination environment of carboxylate-bridged diiron proteins by tethering a small, dangling internal carboxylate, (CH2)nCOOH, to phenol-imine macrocyclic ligands (H3PIMICn). In the presence of an external bulky carboxylic acid (RCO2H), the ligands react with [Fe2(Mes)4] (Mes = 2,4,6-trimethylphenyl) to afford dinuclear [Fe2(PIMICn)(RCO2)(MeCN)] (n = 4-6) complexes. X-ray diffraction studies revealed structural similarities between these complexes and the reduced diiron active sites of proteins such as Class I ribonucleotide reductase (RNR) R2 and soluble methane monooxygenase hydroxylase. The number of CH2 units of the internal carboxylate arm controls the diiron core geometry, affecting in turn the anodic peak potential of the complexes. As functional synthetic models, these complexes facilitate the oxidation of C-H bonds in the presence of peroxides and oxo transfer from O2 to an internal phosphine moiety.
- Wang, Fang,Becker, Sabine,Minier, Mikael A.,Loas, Andrei,Jackson, Megan N.,Lippard, Stephen J.
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supporting information
p. 11050 - 11058
(2017/09/26)
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- A marine natural product (R, Z) - 24-methyl-twenty-five carbon -16-butene -2,4-diyne -1,6-diol and its antimer synthesis method
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The invention relates to a synthetic method of a marine natural product namely (R, Z)-24-methyl-25-carbon-16-butylene-2,4-diyne-1,6-diol and an enantiomer thereof, and belongs to the field of chemical synthesis. The synthetic method comprises the following steps: firstly, preparing long chain alkyl iodide by using a series of simple reactions including bromination, oxidation, esterification, reduction and the like; and then, performing multiple steps of reactions including coupling, dislocation, oxidation, selective reduction, asymmetric alkynylation addition, esterification, hydrolysis and the like by taking propargyl alcohol and the long chain alkyl iodide as starting materials to synthesize the marine natural product namely (R, Z)-24-methyl-25-carbon-16-butylene-2,4-diyne-1,6-diol and the enantiomer thereof, wherein the key step is that trimethylsilylacetylene and alkynal are subjected to asymmetric addition reaction to generate alkynol segments with high optical purity by one step. The synthetic method provided by the invention reports the synthesis of the natural product of the type for the first time, and has the characteristics of simple and convenient steps, relatively high total yield, good product stereoselectivity and the like, and the optical purity of each of the two types of synthesized products is more than 99%ee.
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Paragraph 0013; 0061-0062
(2020/05/06)
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- Total Syntheses of (R)-Strongylodiols C and D
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The first total syntheses of two marine natural products, (R)-strongylodiols C and D, with 99% ee were achieved. The key steps of the strategy include the zipper reaction of an alkyne, the asymmetric alkynylation of an unsaturated aliphatic aldehyde catalyzed with Trost's ProPhenol ligand, and the Cadiot-Chodkiewicz cross-coupling reaction of a chiral propargylic alcohol with a bromoalkyne.
- Liu, Feipeng,Zhong, Jiangchun,Li, Shuoning,Li, Minyan,Wu, Lin,Wang, Qian,Mao, Jianyou,Liu, Shikuo,Zheng, Bing,Wang, Min,Bian, Qinghua
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p. 244 - 247
(2016/02/05)
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- A marine natural product (R) - 24-methyl-twenty-five carbon -2, 4, 16- three alkyne -1,6-diol and its antimer synthesis method
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The invention discloses a synthetic method for a marine natural product (R)-24-methyl-pentacosa-2,4,16-trialkynyl-1, 6-diol and enantiomer thereof, which belongs to the field of chemical synthesis. According to the invention, propargyl alcohol is used as a starting material, and a plurality of steps of reactions like coupling, transposition, oxidation, selective reduction, asymmetric alkynylation addition, esterification and hydrolysis are carried out to synthesize the marine natural product and enantiomer thereof; a key step is that trimethyl silicon-based acetylene and alkynal undergo asymmetric addition so as to produce a high-optical purity alkynol fragment in one step; and long-chain iodoalkane added in the process of synthesis is prepared through a series of simple reactions including bromination, oxidation, esterification, reduction and the like, so reaction route is greatly shortened. The synthesis of the natural product provided by the invention is reported for the first time; the synthetic method has the characteristics of simple steps, high total yield, good product stereoselectivity, etc.; and the optical purities of the products with two configurations are both greater than 99% ee.
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- The discovery and optimization of novel dual inhibitors of topoisomerase ii and histone deacetylase
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A novel class of podophyllotoxin derivatives have been designed and synthesized based on the synergistic antitumor effects of topoisomerase II and histone deacetylase inhibitors. Their inhibitory activities towards histone deacetylases and Topo II and their cytotoxicities in cancer cell lines were evaluated. The aromatic capping group connection, linker length and zinc-binding group were systematically varied and preliminary conclusions regarding structure-activity relationships are discussed. Among all of the synthesized hybrid compounds, compound 24d showed the most potent HDAC inhibitory activity at a low nanomolar level and exhibited powerful antiproliferative activity towards HCT116 colon carcinoma cells at a low micromolar level. Further exploration of this series led to the discovery of potent dual inhibitor 32, which exhibited the strongest in vitro cytotoxic activity.
- Zhang, Xuan,Bao, Bin,Yu, Xiuhua,Tong, Linjiang,Luo, Yu,Huang, Qingqing,Su, Mingbo,Sheng, Li,Li, Jia,Zhu, Hong,Yang, Bo,Zhang, Xiongwen,Chen, Yi,Lu, Wei
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p. 6981 - 6995
(2013/11/06)
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- Carbon-carbon bond fission on oxidation of primary alcohols to carboxylic acids
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α-Carbon-carbon bond cleavage is shown to be a general side reaction accompanying the oxidation of unbranched primary alcohols to the corresponding carboxylic acids using HNO3, CrO3/H2SO 4/H2O/acetone, CrO3/CH3COOH, PDC/DMF, H5IO6/CrO3, KMnO4/H +, KMnO4/HO-, NiCl2/NaClO, TEMPO/PhI(OAc)2. Therefore, the product formed is always contaminated with a carboxylic acid containing one carbon atom less. Systems such as PhI(OAc)2/TEMPO or H5IO6/CrO 3/CH3CN reduce to a minimum the content of this impurity. Temperature, the order of reagent addition, and additives such as oxalic acid or cerium salts produce a profound effect on the formation of the undesirable impurity during the Jones oxidation of primary alcohols.
- Bekish, Andrei V.
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p. 3082 - 3085
(2012/07/28)
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- Synthesis of the diastereomers of dethiobiotin using the conjugate addition of 4-phenyloxazolidin-2-one to a nitroalkene
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Natural D-dethiobiotin and its three stereoisomers were prepared from a single nitroalkene 2. Conjugate addition of the potassium salt of (R)-4-phenyloxazolidin-2-one 3 to 2 led to two diastereomeric nitro compounds 6 and 7. Their enantiomers were prepared from (S)-3. These compounds were converted in three analogous steps into the dethiobiotin isomers as their methyl esters.
- Lucet, Denis,Heyse, Philippe,Gissot, Arnaud,Le Gall, Thierry,Mioskowski, Charles
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p. 3575 - 3579
(2007/10/03)
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- Orthocarbonsaeure-ester mit 2,4,10-Trioxaadamantanstruktur als Carboxylschutzgruppe; Verwendung zur Synthese von substituierten Carbonsaeuren mit Hilfe von Grignard-Reagenzien
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The surprising stability of 2,4,10-trioxa-3-adamantyl derivatives 1 against nucleophilic substitution by organomagnesium compounds is discussed and shown to be caused by unfavourable stereoelectronic and steric factors governing the substitution of these cage compounds (Scheme 2).As a consequence, a number of Grignard reagents 2 containing the carboxyl group masked as 2,4,10-trioxa-3-adamantyl group could be prepared and have been reacted in a second step with various electrophiles (cf.Scheme 4).In the products 7-13 and 15b the carboxyl masking group is removed by mild ac id hydrolysis and saponification (cf.Scheme 3) to yield the corresponding acids 16a-21a, 22, and 23a.Acids 21a and 23a have been further transformed to give the macrocyclic lactones 24 and 26, isolated from Galbanum oleo-gum-resin, and acid 22 to give 12-methyl-13-tridecanolide (25), isolated from Angelica root oil.In addition 1-bromo-ω-(2,4,10-trioxa-3-adamantyl)alkanes 1c and 1b have been used to synthesize (+/-)-methyl recifeiolate (29b) and pure cis-ambrettolic acid ((Z)-32a).
- Voss, Gundula,Gerlach, Hans
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p. 2294 - 2307
(2007/10/02)
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