%0 Journal Article
%T Development of Guanidine-Bisurea Bifunctional Organocatalyst Bearing Chirality at the Inner and Outer Sides of the Urea Groups, and Application to Enantioselective ¦Á-Hydroxylation of Pyranoindolizine Intermediate for Camptothecin Synthesis
%A Minami Odagi
%A Tatsuya Watanabe
%A Kazuo Nagasawa
%J Symmetry
%P 43-52
%D 2015
%I MDPI AG
%R 10.3390/sym7010043
%X Pyranoindolizine is a tricyclic structure found in various biologically active compounds, such as camptothecin (CPT) and its derivatives. In the case of CPTs, the chirality at the ¦Á-position in the ¦Á-hydroxyl lactone moiety of pyranoindolizine is important for the antitumor activity. This paper deals with enantioselective oxidation of the ¦Á-position in pyranoindolizine lactone, which corresponds at C20 in CPT, with cumene hydroperoxide (CHP) in the presence of newly synthesized guanidine-bisurea bifunctional organocatalysts bearing chirality on both the inner and outer sides of the urea groups.
%K ¦Á-hydroxylation
%K pyranoindolizine
%K camptothecin
%K organocatalyst
%U http://www.mdpi.com/2073-8994/7/1/43