. 2021 Nov 8;26(21):6742. doi: 10.3390/molecules26216742
© 2021 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 (https://creativecommons.org/licenses/by/4.0/).
Scheme 1.
Synthetic route to obtain 4(a–c) and 5(a–c).