Electrochemical Synthesis of Amino Derivatives of Biflavonoids

Abstract

We demonstrated earlier that biflavonoids could be prepared electrochemically [1]. The broad spectrum of biological activity of flavonoids is related mainly to the ability of the hydroxyls to bond to various biological targets, acting as both H-bond acceptors and donors [2, 3]. Amines are known to possess similar properties [4]. In continuation of research on the electrochemistry of flavonoids, we studied the possible electrochemical synthesis of amino derivatives of biflavonoids. We used the flavonol isorhamnetin, which was isolated earlier by us from Alhagi pseudalhagi (M. Bieb.) Fisch. The amine sources were morpholine and dimethylamine. A solution of isorhamnetin (1 mmol), LiClO4 (100 mmol), and amine (6 mmol) in MeCN (100 mL) was electrolyzed in a diaphragm cell at anodic current density 5 mA/cm2 for 3.5 h. The anode was a Pt plate with working surface 2 cm2. About 90% of the MeCN was distilled from the anode compartment when the electrolysis was finished. The residue was placed on a column of silica gel (Porokvarts PKN-200) and eluted in gradient mode by CHCl3–EtOH at 5 mL/min. The EtOH concentration was varied in the range 10–30%. The principal products of recrystallization from Me2CO (0.29 0.01 g yield for electrolysis with morpholine and 0.22 0.01 g, with Me2NH) were red and yellow powders, the physicochemical and spectral characteristics of which were determined by known methods.