Synonyms: A-Neo-18a-olean-3(5)-ene, 19b,28-epoxy- (7CI,8CI);A-Neoolean-3(5)-ene, 19,28-epoxy-, (18a,19b)-; 11,7a-(Epoxymethano)-7aH-cyclopenta[a]chrysene,1,2,4,5,5a,5b,6,7,8,9,10,11,11a,11b,12,13,13a,13b-octadecahydro-5a,5b,10,10,13b-pentamethyl-3-(1-methylethyl)-,[5aR-(5aa,5bb,7aa,11a,11ab,11ba,13ab,13ba)]-; 19b,28-Epoxy-4,5-seco-3,5-cyclo-18a-olean-3(5)-ene; a-Allobetulin; a-Apoallobetulin