. 2020 Jul 19;25(14):3281. doi: 10.3390/molecules25143281
© 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 23.
Stable, protonated urea derivatives.