(4S,4aR,8aS)-4-ethyl-3-oxo-3,4,4a,5,8,8a-hexahydro-1H-isochromene-4-carbonitrile

(4S,4aR,6S,7S,8aS)-4-ethyl-7-hydroxyoctahydro-3H-6,4-(epiminomethano)isochromen-3-one

(4S,4aR,6S,7S,8aS)-9-benzoyl-4-ethyl-7-hydroxyoctahydro-3H-6,4-(epiminomethano)isochromen-3-one

(4S,4aR,6S,8aS)-9-benzoyl-4-ethylhexahydro-1H-6,4-(epiminomethano)isochromene-3,7-dione

(4S,4aR,6S,11cR)-12-benzoyl-7-benzyl-4-ethyl-4,4a,5,6,7,11c-hexahydro-6,4-(epiminomethano)pyrano[4,3-c]carbazol-3(1H)-one