1 9UM 3-(bromomethyl)-2,5,6-trimethyl-1h,7h-pyrazolo[1,2-a]pyrazole-1,7-dione 1.000 2 6E3 2,3,5,6-tetramethyl-1h,7h-pyrazolo[1,2-a]pyrazole-1,7-dione 0.933