. 2019 Nov 25;24(23):4285. doi: 10.3390/molecules24234285
© 2019 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 1.
Preparation of 3a–e and 4a–e derivatives.