“…They were discovered in 1935 by Earl and Mackney 1 and their mesoionic structure was assigned in 1949 by Baker and Ollis. 2 Sydnones present an array of biological properties such as antibacterial, 3,5 antifungal, 3,5 antimicrobial, [4][5][6] anticancer, 5,7 antiproliferative, 8 anti-HIV, 8 anti-inflammatory and analgesic activities. 9 Sydnones ( Figure 1) undergo two main chemical reactions, namely 1,3-dipolar cycloaddition to form pyrazoles and electrophilic substitution at C-4.…”