- Hydration of Cyanohydrins by Highly Active Cationic Pt Catalysts: Mechanism and Scope
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Cyanohydrins (α-hydroxy nitriles) are a special type of nitriles that readily decompose into hydrogen cyanide (HCN) and the corresponding carbonyl compounds. Hydration of cyanohydrins that are readily available through cyanation of aldehydes and ketones provides the most straightforward route to valuable α-hydroxyamides. However, due to low stability of cyanohydrins and deactivation of the catalysts by the released HCN, catalytic direct hydration of cyanohydrins still remains largely unsolved. As a general trend, cyanohydrins containing bulkier substituents, such as α,α-diaryl cyanohydrins, degrade more quickly and thus are more difficult to be hydrated. Here, we report development of cationic platinum catalysts that exhibit high reactivity for hydration of various cyanohydrins. Detailed mechanistic investigations for hydration of nitriles by (PμP)Pt(PR2OH)X(OTf) reveal a catalytic cycle involving the formation of a five-membered metallacyclic intermediate and subsequent hydrolysis via attacking on the phosphorus of the secondary phosphine oxide (PR2OH) ligand by H2O. We discovered that Pt catalyst A bearing the electron-rich, appropriately small-bite-angle bisphosphine ligand provides super reactivity for hydration of cyanohydrins. The hydration reactions catalyzed by A proceed at ambient temperatures and occur with a wide variety of cyanohydrins, including the most difficult α,α-diaryl cyanohydrins, with good turnover numbers.
- Li, Chengcheng,Chang, Xiao-Yong,Huo, Luqiong,Tan, Haibo,Xing, Xiangyou,Xu, Chen
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p. 8716 - 8726
(2021/07/26)
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- Oxadiazole Amine Derivative Compounds as Histone Deacetylase 6 Inhibitor, and the Pharmaceutical Composition Comprising the same
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The present invention relates to a novel compound having an activity of inhibiting histone deacetylase 6 (HDAC6), an optical isomer thereof or a pharmaceutically acceptable salt thereof, a use thereof for preparation of a drug for treatment, a pharmaceutical composition comprising the same, a treatment method using the composition, and a method for preparing the same. The novel compound, an optical isomer thereof or a pharmaceutically acceptable salt thereof according to the present invention has an activity of inhibiting histone deacetylase 6 (HDAC6), and is effective for preventing or treating HDAC6-related diseases, including infectious diseases; neoplasm; endocrine, nutritional and metabolic diseases; mental and behavior disorders; nerve disorders; eye and adnexa diseases; cardiovascular diseases; respiratory diseases; digestive organ diseases; skin and subcutaneous tissue diseases; musculoskeletal and connective tissue diseases; or congenital malformation, deformation and chromosomal abnormality.COPYRIGHT KIPO 2017
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- Bridging C?H Activation: Mild and Versatile Cleavage of the 8-Aminoquinoline Directing Group
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8-Aminoquinoline has emerged as one of the most powerful bidentate directing groups in history of C?H activation within the last decade. However, cleavage of its robust amide bond has shown to be challenging in several cases, thus jeopardizing the general synthetic utility of the method. To overcome this limitation, we herein report a simple oxidative deprotection protocol. This transformation rapidly converts the robust amide to a labile imide, allowing subsequent cleavage in a simple one-pot fashion to rapidly access carboxylic acids or amides as final products.
- Berger, Martin,Chauhan, Rajan,Rodrigues, Catarina A. B.,Maulide, Nuno
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p. 16805 - 16808
(2016/11/16)
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