Synthesis of novel tricyclic 2H,7H-furo[3′,4′:6,7]cyclohepta-[1,2-b]pyran system
作者:M. Yu. Arsenyeva、V. G. Arsenyev
DOI:10.1007/s10593-009-0199-5
日期:2008.11
The reaction of 8-hydroxy-1,3-dimethyl-4H-cyclohepta[c]furan-4-one with the ethoxymethylene derivatives of malononitrile or ethyl cyanoacetate in the presence of KOH gave noncyclic cyanovinyl derivatives as their potassium salts rather than the expected alpha-pyrone derivatives. They are smoothly cyclized to the target alpha-pyrones by refluxing with acid. The corresponding 3-benzamido-2H-pyran-2-ones can be obtained in a single vessel from the 2-aryl-4-ethoxymethylene-4H-1,3-oxazol-5-ones using the same scheme.
New 13-vinyl derivatives of berberine: synthesis and characterization
作者:Oleg D. Demekhin、Oleg N. Burov、Mikhail E. Kletskii、Anton V. Lisovin、Sergey V. Kurbatov、Elena A. Bereznyak、Alena V. Trishina
DOI:10.1007/s10593-022-03067-w
日期:2022.2
13-vinylberberines were stable in their reduced form due to significant intramolecular electron density transfer from berberine ringsystem to the vinyl moiety bearing electron-withdrawing groups. It was demonstrated that berberine derivatives may exist not only in ion pair form consisting of organic cation and inorganic anion, but also as zwitterionic structures featuring significant intramolecular charge transfer