1 3 4 6 7 8 hexahydro 2h pyrimido 1 2 a July 8, 2019 16 32 64 128 1 3 4 6 7 8-hexahydro-4 6 6 7 8 8-hexamethylindeno 5 6-c pyran 1 3 4 6 7 8-hexahydro-2h-pyrimido 1 2-a pyrimidine 2 3 4 6 7 8-hexahydro-1h-pyrimido 1 2-a pyrimidine
