4a H-3,5 ,8 -trimethyl-4,4a,9-tetrahydro-naphtho(2,3-b)-furan-8-one
4a h-3,5 ,8 -trimethyl-4,4a,9-tetrahydro-naphtho(2,3-b)-furan-8-one
4a alpha H-3,5 alpha,8 alpha beta-trimethyl-4,4a,9-tetrahydro-naphtho(2,3-b)-furan-8-one
4a alpha h-3,5 alpha,8 alpha beta-trimethyl-4,4a,9-tetrahydro-naphtho(2,3-b)-furan-8-one