Cationic zirconocene- or hafnocene-based Lewis acids in organic synthesis: glycoside–flavonoid analogy
作者:Ken Ohmori、Keisuke Hatakeyama、Hiroki Ohrui、Keisuke Suzuki
DOI:10.1016/j.tet.2003.08.076
日期:2004.2
Cationic metallocene species, generated from Cp2MCl2 and AgClO4 (M=Zr, Hf), were used for the glycosylation of catechin derivative 2, enabling a concise synthesis of a glycosyl flavonoid, astilbin (1). Further study revealed the efficiency of this Lewis acidic species for S(N)1-type activation of the C(4) position of catechin derivative 11, enabling selective substitution with various nucleophiles. (C) 2003 Elsevier Ltd. All rights reserved.