共查询到20条相似文献，搜索用时 15 毫秒
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A simple and effective synthesis of enantiomerically pure 2-(N-aryl-, N-alkyl-aminomethyl)aziridines from (2S)-N-tritylaziridine-2-carboxylic acid methyl ester has been developed. Treating of this key ester with several primary and secondary amines in the presence of AlMe3 provided the corresponding chiral N-trityl-2-carboxamides, and their reduction performed with different reagents resulted in the formation of the expected 2-(aminomethyl)aziridines. The choice of reaction conditions allows to either keep or leave the trityl substituent in the product. Such 2-(aminoalkyl)aziridines have shown very high catalytic efficiency in the asymmetric arylation of aldehydes and in other testing asymmetric reactions. On the other hand, homochiral N-trityl-2-carboxamides are interesting building blocks for the synthesis of various biologically active compounds. 相似文献
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A novel and efficient approach for the synthesis of 1α, 24(R)-dihydroxyvitamin D3 (tacalcitol) starting from readily available enone 1 has been achieved with high stereoselectivity. The key step involved in the synthesis of tacalcitol was the stereoselective reduction of enone 1 using borane as the reducing agent, and the effects of the critical reaction parameters such as temperature, various borane complexes have been examined. Finally, tacalcitol was obtained in five steps from enone 1 with an overall yield of 32% and a ratio of 24-R/S = 95/5. 相似文献
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Kosaku Tanaka Yusuke Honma Chihiro Yamaguchi Lina Aoki Minami Saito Momoko Suzuki Kazuhiro Arahata Kaoru Kinoshita Kiyotaka Koyama Kenichi Kobayashi Hiroshi Kogen 《Tetrahedron》2019,75(8):1085-1097
The relative and absolute configurations of L-755,807 were established through total synthesis. All four possible stereoisomers were prepared via a convergent synthetic strategy, including a novel diastereoselective Darzens reaction of an α-alkoxy aldehyde with di-tert-butyl bromomalonate, an E-selective Horner–Wadsworth–Emmons reaction, and late-stage coupling of the ring and side-chain segments. Additionally, biological evaluation of the synthesized compounds revealed their potent inhibitory activities (IC50?=?5–21?μM) against amyloid-β aggregation for the treatment of Alzheimer's disease. 相似文献
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Thomas K. David Nayak K. Prashanth M. Rajendraswami Devendrareddy Pallalu Arlindo L. Castelhano Michael J. Kates Anna L. Blobaum Carrie K. Jones Kyle A. Emmitte P. Jeffrey Conn Craig W. Lindsley 《Tetrahedron letters》2017,58(36):3554-3558
This communication details the kilogram-scale synthesis of N-(5-fluoropyridin-2-yl)-6-methyl-4-(pyrimidin-5-yloxy)picolinamide (VU0424238, auglurant), a novel mGlu5 negative allosteric modulator (NAM) developed as an alternative treatment for depression. The process highlights a challenging pyridine N-oxidation sequence, an SNAr reaction, and the elimination of all chromatography steps (required in the medicinal chemistry route) with replacement by highly efficient recrystallizations (save one silica plug). The improved process was utilized for the preparation of a 1.2 kg toxicology batch, as well as a 2.82 kg GMP batch to support the Phase I trial, in very high purity (99.8%). 相似文献
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Michael D. Visco Jonathan Attard Yong Guan Anita E. Mattson 《Tetrahedron letters》2017,58(27):2623-2628
Select hydrogen bond donors can catalyze reactions of ion pairs through the recognition of anions. This mode of action can be exploited in enantioselective catalysis if a suitable chiral hydrogen bond donor is applied. Beyond just anionic recognition, an enantioselective anion-binding catalyst often must host numerous non-covalent interactions, including hydrogen bonding, general base, π-π, and π-cation, to achieve high levels of enantiocontrol. Anion-binding catalysts can be strategically designed to support those non-covalent interactions required to render a process highly stereoselective. Tactics applied in anion-binding catalyst development include enhancing arene substituents for improved π-stacking, linking two anion-binding units together on a single scaffold, expanding types of functional groups for anion recognition, and building frameworks with bifunctional modes of action. The intent of this digest is to highlight observations that suggest as anion-binding catalyst designs advance, their associated synthetic methodologies for complex molecule construction become increasingly impressive. 相似文献
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《Comptes Rendus Chimie》2016,19(6):733-748
Methods of Green Chemistry are in the meantime established in process design for extraction of natural products [1]. Moreover, natural products do have the inherent societal benefit of being a priori bio-degradable and therefore do not cause any additional waste-water and recycling problems in hospitals, cities and municipalities or environmental enrichment [2].Nevertheless, those inherent benefits could be easily compromised if they are not combined with the design and operation of fully integrated processes in manufacturing. One isolated action of Green Chemistry is not sufficient to gain the entrepreneurial balance of economy and ecology with competitive manufacturing, new marketable products, and sustainability. While any process modification could be implemented in substituting simply one existing step, a fully integrated new process needs to be set up to exceed the existing benchmark or best practice and to be transferred into manufacturing.Finding alternative solvents and enhancing mass transfer in extraction need to be integrated. This integration into a complete process from extraction over purification to formulation, considering recycling at all steps, is a complex task which could not be fulfilled on a purely experimental basis. The efforts would be too high and costly. Therefore, the paper reviews the existing status shortly and exemplifies based on a case study, choosing 10-deacetylbaccatin III as a typical example, a theoretical approach in thermodynamics and process modeling, and how they can contribute to an alternative process design. Still, these steps in conceptual process design and basic engineering seem to be the major challenge in industrial acceptance of alternative ideas.The authors have described the transfer into innovative manufacturing concepts already elsewhere [1], [2], [3]. 相似文献
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