. 2020 Aug 10;25(16):3633. doi: 10.3390/molecules25163633
© 2020 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 (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
Figure 2.
Chemical structures of 3a, 3b and 1.