Summary of main observation and conclusion Schisandraceae triterpenoids are novel natural products that contain highly fused ring systems bearing multiple chiral centers surrounding. Some of them exhibit promising bio...Summary of main observation and conclusion Schisandraceae triterpenoids are novel natural products that contain highly fused ring systems bearing multiple chiral centers surrounding. Some of them exhibit promising bioactivities, such as antitumor, anti‐HIV, etc. In this article, we describe our efforts to the collective total synthesis of schilancidilactones A, B, schilancitrilactones A, B, C, and 20‐epi‐schilancitrilactone A from common precursors. An intramolecular radical cyclization, late‐stage halogenation and AIBN‐mediated or Ni‐catalyzed intermolecular radical cross coupling reaction were employed as the key steps.展开更多
In this work,thermodynamic and kinetic factors that affect formation and phase transformation process of different solid forms of levofloxacin hydrochloride were investigated in detail.Dynamic vapor sorption experimen...In this work,thermodynamic and kinetic factors that affect formation and phase transformation process of different solid forms of levofloxacin hydrochloride were investigated in detail.Dynamic vapor sorption experiments(DVS)and varying temperature-powder X-ray diffraction(VT-PXRD)experiments were carried out to study moisture-dependent stability,thermal stability as well as the transformation process between Form I and Form II.Critical water activities of levofloxacin hydrochloride were determined in temperature range of 5.0–45.0°C.Raman spectroscopy was applied to in situ monitor the temperature-induced phase transformation and the hydration process of levofloxacin hydrochloride,and one possible mechanism consisting of multiple chemical equilibria was proposed to analyze the effect of thermodynamic and kinetic factors on the formation and transformation of different solid forms.Results show that the anhydrate,Form II would transform to the monohydrate,Form I more easily with the increasing water content.And the transition point moves toward higher water contents as the temperature increases.The results suggested that,except for thermodynamic factors,kinetic factors also play an essential role in controlling the solid forms of polymorphic compounds.展开更多
文摘Summary of main observation and conclusion Schisandraceae triterpenoids are novel natural products that contain highly fused ring systems bearing multiple chiral centers surrounding. Some of them exhibit promising bioactivities, such as antitumor, anti‐HIV, etc. In this article, we describe our efforts to the collective total synthesis of schilancidilactones A, B, schilancitrilactones A, B, C, and 20‐epi‐schilancitrilactone A from common precursors. An intramolecular radical cyclization, late‐stage halogenation and AIBN‐mediated or Ni‐catalyzed intermolecular radical cross coupling reaction were employed as the key steps.
基金This work was supported by Tianjin Natural Science Foundation(grant numbers 18JCZDJC38100 and 18JCYBJC40800).
文摘In this work,thermodynamic and kinetic factors that affect formation and phase transformation process of different solid forms of levofloxacin hydrochloride were investigated in detail.Dynamic vapor sorption experiments(DVS)and varying temperature-powder X-ray diffraction(VT-PXRD)experiments were carried out to study moisture-dependent stability,thermal stability as well as the transformation process between Form I and Form II.Critical water activities of levofloxacin hydrochloride were determined in temperature range of 5.0–45.0°C.Raman spectroscopy was applied to in situ monitor the temperature-induced phase transformation and the hydration process of levofloxacin hydrochloride,and one possible mechanism consisting of multiple chemical equilibria was proposed to analyze the effect of thermodynamic and kinetic factors on the formation and transformation of different solid forms.Results show that the anhydrate,Form II would transform to the monohydrate,Form I more easily with the increasing water content.And the transition point moves toward higher water contents as the temperature increases.The results suggested that,except for thermodynamic factors,kinetic factors also play an essential role in controlling the solid forms of polymorphic compounds.
