. 2011 May 25;16(6):4339–4347. doi: 10.3390/molecules16064339
© 2011 by the authors;
licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution license (http://creativecommons.org/licenses/by/3.0/).
Scheme 1.
Synthesis of heterocyclic derivatives 15-20.