- Flow reactor approach for the facile and continuous synthesis of efficient Pd@Pt core-shell nanoparticles for acceptorless dehydrogenative synthesis of pyrimidines from alcohols and amidines
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Carbon supported Pd@Pt core-shell nanoparticles catalyst was prepared in a flow reactor toachieve enhanced catalytic activities with low Pt loading for the acceptorless dehydrogenative synthesis of pyrimidines. Spectroscopic (XAS analysis) and microscopic (HAADF-STEM) techniques reveled that the core-shell structure was formed by the applied preparation method. The Pd@Pt/PVP (polyvinylpyrrolidone)/C catalyst showed the activity for the three component one pot synthesis of pyrimidines through a series of consecutive reactions including oxidation of alcohols, C[sbnd]C, and C[sbnd]N coupling, followed by heterocyclization and dehydrogenation employing various primary alcohols, secondary alcohols, and amidines. The reaction mechanism on Pd@Pt/PVP/C catalyst was explored by comparison with the control experiments.
- Poly, Sharmin Sultana,Hashiguchi, Yuta,Sultana, Asima,Nakamura, Isao,Shimizu, Ken-ichi,Yasumura, Shunsaku,Fujitani, Tadahiro
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- Heterogeneously Catalyzed Selective Decarbonylation of Aldehydes by CeO2-Supported Highly Dispersed Non-Electron-Rich Ni(0) Nanospecies
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Aldehyde decarbonylation has been extensively investigated, primarily using noble-metal catalysts; however, nonprecious-base-metal-catalyzed aldehyde decarbonylation has been hardly reported. We have established an efficient selective aldehyde decarbonylation reaction with a broad substrate scope and functional group tolerance utilizing a heterogeneous Ni(0) nanospecies catalyst supported on CeO2. The high catalytic performance is attributable to the highly dispersed and non-electron-rich Ni(0) nanospecies, which possibly suppress a side reaction producing esters and adsorbed CO-derived inhibition of the catalytic turnover, according to detailed catalyst characterization and kinetic evaluation.
- Matsuyama, Takehiro,Yatabe, Takafumi,Yabe, Tomohiro,Yamaguchi, Kazuya
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p. 13745 - 13751
(2021/11/17)
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- Acceptorless Dehydrogenative Synthesis of Pyrimidines from Alcohols and Amidines Catalyzed by Supported Platinum Nanoparticles
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A one-pot, acceptorless dehydrogenative method, using a carbon-supported Pt catalyst (Pt/C) along with KOtBu, has been developed for the synthesis of 2,4,6-trisubstituted pyrimidines from secondary and primary alcohols, and amidines. The reaction takes place efficiently using a wide range of substrate scopes (32 examples with isolated yields up to 92%). The Pt/C catalyst that promotes this process is reusable and has a higher turnover number (TON) than those employed in previously reported methods. The results of mechanistic studies suggest that the process takes place through a pathway that begins with Pt-catalyzed acceptorless dehydrogenation of the alcohol substrate, which is followed by sequential condensation, cyclization, and dehydrogenation. Measurements of the turnover frequency combined with the results of density functional theory calculations on different metal surfaces suggest that the adsorption energy of H on the Pt surface is optimal for the acceptorless dehydrogenation process, which causes the higher catalytic activity of Pt over those of other metals.
- Sultana Poly, Sharmin,Siddiki, S. M. A. Hakim,Touchy, Abeda S.,Ting, Kah Wei,Toyao, Takashi,Maeno, Zen,Kanda, Yasuharu,Shimizu, Ken-Ichi
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p. 11330 - 11341
(2019/01/03)
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- Synthetic method of rosuvastatin calcium key intermediate
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The invention discloses a synthetic method of a rosuvastatin calcium key intermediate. The synthetic method particularly comprises the following steps: carrying out a condensation reaction between fluoroacetophenone and ethyl isobutyrate under the condition of using sodium as alkali by using isopropyl alcohol as a solvent to prepare 1-(4-fluorophenyl)-4-methyl amyl-1,3-diketone; then carrying out a ring closing reaction between the 1-(4-fluorophenyl)-4-methyl amyl-1,3-diketone and methylguanidine hydrochloride by using isopropanol as a solvent to obtain 4-(4-fluorophenyl)-6-isopropyl-N-methyl pyrimidine-2-amine; carrying out a substitution reaction between the 4-(4-fluorophenyl)-6-isopropyl-N-methyl pyrimidine-2-amine and methanesulfonyl chloride by using dichloromethane as a solvent to obtain 4-(4-fluorophenyl)-6-isopropyl-2-[(N-methyl-N-methanesulfonyl) amino] pyrimidine; finally, carrying out a Vilsmeier reaction between the 4-(4-fluorophenyl)-6-isopropyl-2-[(N-methyl-N-methanesulfonyl) amidogen] pyrimidine and DMF (Dimethyl Formamide) as well as phosphoryl chloride to obtain a target compound. The method disclosed by the invention has the advantages of being simple to operate, low in raw material price, high in availability of used raw materials, mild in reaction conditions, low in equipment requirements and production cost, easy for scale production and the like, and has significance industrial application value.
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Paragraph 0037; 0038; 0039
(2016/10/10)
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- Method used for synthesizing rosuvastatin calcium key intermediate
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The invention discloses a method used for synthesizing a rosuvastatin calcium intermediate represented by formula I. The reaction route is disclosed in the invention. Raw materials used in the method are low in toxicity; synchronous recycling of used solvents can be realized; expensive materials such as 4-methylmorpholine-N-oxide, TPAP (tetrapropylammonium perruthenate), and DIBAL-H are not used, so that production cost is reduced effectively; reaction conditions are mild; energy consumption is low; no special reaction equipment is needed; operation is simple; one-pot preparation can be realized; and the method is convenient for large-scale production.
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Paragraph 0016; 0032; 0033; 0034
(2016/10/10)
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- Preparation method of rosuvastatin calcium key intermediate
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The invention discloses a preparation method of a rosuvastatin calcium key intermediate, i.e. a compound as shown in a formula I. The preparation method comprises the following steps: a, carrying out a reaction between fluoroacetophenone and ethyl isobutyrate to prepare a compound as shown in a formula IV; b, carrying out a reaction between the obtained compound IV and methylguanidine hydrochloride as well as potassium hydroxide to obtain a compound as shown in a formula III; c, carrying out a reaction between the compound III and triethylamine as well as methanesulfonyl chloride to prepare a compound as shown in a formula II; d, carrying out a reaction between the compound as shown in the formula II and N,N-dimethylformamide as well as phosphorus oxychloride to obtain the compound as shown in the formula I. A reaction route of the preparation method is as shown in the following: (referring to the specification). The method disclosed by the invention has the advantages of being simple to operate, low in raw material price, high in availability of used raw materials, mild in reaction conditions, low in equipment requirements and production cost, easy for scale production and the like, and has significance industrial application value.
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Paragraph 0030; 0031; 0032
(2016/12/22)
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- A sustainable multicomponent pyrimidine synthesis
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Since alcohols are accessible from indigestible biomass (lignocellulose), the development of novel preferentially catalytic reactions in which alcohols are converted into important classes of fine chemicals is a central topic of sustainable synthesis. Multicomponent reactions are especially attractive in organic chemistry as they allow the synthesis of large libraries of diversely functionalized products in a short time when run in a combinatorial fashion. Herein, we report a novel, regioselective, iridium-catalyzed multicomponent synthesis of pyrimidines from amidines and up to three (different) alcohols. This reaction proceeds via a sequence of condensation and dehydrogenation steps which give rise to selective C-C and C-N bond formations. While the condensation steps deoxygenate the alcohol components, the dehydrogenations lead to aromatization. Two equiv of hydrogen and water are liberated in the course of the reactions. PN5P-Ir-pincer complexes, recently developed in our laboratory, catalyze this sustainable multicomponent process most efficiently. A total of 38 different pyrimidines were synthesized in isolated yields of up to 93%. Strong points of the new protocol are its regioselectivity and thus the immediate access to pyrimidines that are highly and unsymmetrically decorated with alkyl or aryl substituents. The combination of this novel protocol with established methods for converting alcohols to nitriles now allows to selectively assemble pyrimidines from four alcohol building blocks and 2 equiv of ammonia.
- Deibl, Nicklas,Ament, Kevin,Kempe, Rhett
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supporting information
p. 12804 - 12807
(2015/10/28)
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- PROCESS FOR PREPARING PYRIMIDINE DERIVATIVES
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The present invention relates to a process for preparing pyrimidine derivatives, in particular as intermediates useful for preparing pyrimidine derivatives of a class that is effective at inhibiting the biosynthesis of cholesterol in humans, such as HMG-CoA reductase inhibitors, e.g. rosuvastatin.
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Page/Page column 14
(2009/04/25)
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- A new approach to the total synthesis of rosuvastatin
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A new multi-step synthesis of the lipid-lowering agent rosuvastatin, involving two homogeneously catalyzed reaction steps, is described. The key building block, N-[4-(4-fluorophenyl)-5-formyl-6-isopropylpyrimidin-2-yl]-N- methylmethanesulfonamide (2), was prepared by Pd-catalyzed formylation with CO/H2 (1:1, 50 bar, phosphane ligand/substrate ratio of 1:10). Several alternative pathways for the preparation of 2 were also tested, but were found to be inferior. Rosuvastatin precursor 1 was assembled by Wittig coupling of aldehyde 2 and ylide (R)-3, derived from a Rucatalyzed asymmetric hydrogenation. The second stereogenic center was finally created by stereoselective reduction with Et2BOMe and NaBH4 to afford rosuvastatin ethyl ester. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Andrushko, Natalia,Andrushko, Vasyl,Koenig, Gerd,Spannenberg, Anke,Boerner, Armin
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experimental part
p. 847 - 853
(2009/04/11)
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