Diisobutylaluminium hydride （DIBAL-H） promotes secondary rim regioselective bis-de-O-methylation of permethylated β- cyclodextrin （β-CD） to give diol 2. To gain an insight into the mechanism of this remarkable r...Diisobutylaluminium hydride （DIBAL-H） promotes secondary rim regioselective bis-de-O-methylation of permethylated β- cyclodextrin （β-CD） to give diol 2. To gain an insight into the mechanism of this remarkable regioselective behavior, two corresponding permethylated β-CDs with an alcohol function at either 2- or 3-position were synthesized in our previous study. As a step further to this work, the two compounds were subjected to deoxygenation reaction with tributyltin hydride in the present of 2,2＇- azobisisobutyronitrile affording the corresponding 2- and 3-deoxy permethylated β-CD derivatives （19 and 16）. The structures of these two compounds were characterized by 1D and 2D NMR and HRMS. Compounds 16 and 19 were unable to react with DIBAL- H which suggests that O-2A and O-3B are necessary for DIBAL-H promoted bis-de-O-methylation reaction of permethylated β-CD.展开更多
The nitrile compounds are present in a variety of biologically active natural products and pharmaceuticals,and the nitrile groups are versatile synthetic intermediates to other functionalized compounds.Herein,the asym...The nitrile compounds are present in a variety of biologically active natural products and pharmaceuticals,and the nitrile groups are versatile synthetic intermediates to other functionalized compounds.Herein,the asymmetric reduction ofα,β-unsaturated nitriles with water as a hydrogen source is reported.The reaction is catalyzed by the complex of[Ir(COD)Cl]_(2)and(R_(a),S)-Ph-Bn-SiPhox,and allows the preparation of useful enantioenriched chiral 3,3-disubstituted propionitriles with high optical purities in mild conditions.展开更多
Oleanolic acid(OA) and echinocystic acid(EA), two naturally occurring pentacyclic oleanane triterpenes,are gaining increasing attention due to their promising pharmacological activities. Conjugation with amphiphilic ...Oleanolic acid(OA) and echinocystic acid(EA), two naturally occurring pentacyclic oleanane triterpenes,are gaining increasing attention due to their promising pharmacological activities. Conjugation with amphiphilic α(β)-cyclodextrin(CD) via "click chemistry" can improve their solubility and anti-HCV entry potency. In the present work,four water-soluble β-CD-pentacyclic triterpene conjugates were designed and synthesized, in which OA and EA was coupled to one of the primary hydroxyl groups of β-CD via ester and amide bonds. The structures of the conjugates were unambiguously determined by ~1H NMR, ^(13)C NMR and HRMS or MALDI-TOF-MS. All the conjugates showed lower hydrophobicity(AlogP) than their parent compounds and no significant cytotoxicity was found to HL-60, A549, Hela and Bel-7402 cells at concentrations up to 10 μmol/L. Further anti-HCV entry activity and mechanism studies are under way in our laboratory.展开更多
基金Financial support of this study from CNRS is gratefully acknowledged
文摘Diisobutylaluminium hydride （DIBAL-H） promotes secondary rim regioselective bis-de-O-methylation of permethylated β- cyclodextrin （β-CD） to give diol 2. To gain an insight into the mechanism of this remarkable regioselective behavior, two corresponding permethylated β-CDs with an alcohol function at either 2- or 3-position were synthesized in our previous study. As a step further to this work, the two compounds were subjected to deoxygenation reaction with tributyltin hydride in the present of 2,2＇- azobisisobutyronitrile affording the corresponding 2- and 3-deoxy permethylated β-CD derivatives （19 and 16）. The structures of these two compounds were characterized by 1D and 2D NMR and HRMS. Compounds 16 and 19 were unable to react with DIBAL- H which suggests that O-2A and O-3B are necessary for DIBAL-H promoted bis-de-O-methylation reaction of permethylated β-CD.
基金grateful to the National Natural Science Foundation of China(Nos.21961045 and 22061048)the Basic Research Project of Chongqing Academy of Chinese Materia Medica(No.jbky20190028)+2 种基金the Fund Project of Yunnan Key Laboratory of Pharmacology for Natural Products(No.YKLPNP-K2303)Yunnan Provincial Key Laboratory Construction Plan Funding of UniversitiesYunnan Provincial Engineering Research Center Construction Plan Funding of Universities for their financial support.
文摘The nitrile compounds are present in a variety of biologically active natural products and pharmaceuticals,and the nitrile groups are versatile synthetic intermediates to other functionalized compounds.Herein,the asymmetric reduction ofα,β-unsaturated nitriles with water as a hydrogen source is reported.The reaction is catalyzed by the complex of[Ir(COD)Cl]_(2)and(R_(a),S)-Ph-Bn-SiPhox,and allows the preparation of useful enantioenriched chiral 3,3-disubstituted propionitriles with high optical purities in mild conditions.
基金supported by the National Natural Science Foundation of China (Nos. 81573269, 21572015, 21877007, 91753202 and 21702007)and the open funding of the State Key Laboratory of Phytochemistry and Plant Resources in West China
文摘Oleanolic acid(OA) and echinocystic acid(EA), two naturally occurring pentacyclic oleanane triterpenes,are gaining increasing attention due to their promising pharmacological activities. Conjugation with amphiphilic α(β)-cyclodextrin(CD) via "click chemistry" can improve their solubility and anti-HCV entry potency. In the present work,four water-soluble β-CD-pentacyclic triterpene conjugates were designed and synthesized, in which OA and EA was coupled to one of the primary hydroxyl groups of β-CD via ester and amide bonds. The structures of the conjugates were unambiguously determined by ~1H NMR, ^(13)C NMR and HRMS or MALDI-TOF-MS. All the conjugates showed lower hydrophobicity(AlogP) than their parent compounds and no significant cytotoxicity was found to HL-60, A549, Hela and Bel-7402 cells at concentrations up to 10 μmol/L. Further anti-HCV entry activity and mechanism studies are under way in our laboratory.
