O-(Benzotriazol-1-yl)-N,N,N′,N′-tetramethyluronium tetrafluoroborate125700-67-6100 % similar Hbtu94790-37-179 % similar Tctu330641-16-272 % similar Hctu330645-87-957 % similar Hatu148893-10-156 % similar 2-(2-Pyridon-1-yl)-1,1,3,3-tetramethyluronium tetrafluoroborate125700-71-236 % similar N,N,N',N'-Tetramethyl-O-(3,4-dihydro-4-oxo-1,2,3-benzotriazin-3-yl)uronium tetrafluoroborate125700-69-834 % similar