(1S,8R,14S)-6,9-dioxo-15,17-diazatetracyclo[12.2.2.1(3,7).1(8,12)]icosa-3(20),4,6,10,12(19)-tetraen-17-ium-7-ide
(1s,8r,14s)-6,9-dioxo-15,17-diazatetracyclo[12.2.2.1(3,7).1(8,12)]icosa-3(20),4,6,10,12(19)-tetraen-17-ium-7-ide
This is the major tautomer at pH 7.3 of compound 13 of pmid:27690412