. 2020 Jul 29;25(15):3439. doi: 10.3390/molecules25153439
© 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/).
Scheme 1.
Preparative methods of compounds 1–3.