(7R,8S,10bR)-7,8-Dihydroxy-1,5,6,7,8,9,10,10b-octahydro-3H-1,3-oxazolo[4,3-a]isoquinolin-3-one

The title compound, C11H15NO4, was synthesized as an intermediate in a synthesis of the morphine skeleton. The two six-membered rings adopt 4H3 half-chair conformations. The five-membered ring is in an envelope (E) conformation. Chains of the molecules hydrogen bonded through the allylic hydroxyl and carbonyl groups extend along the b axis. These chains are cross-linked along the [101] direction by hydrogen bonds between the adjacent secondary OH group and the allylic O atom [allylic O⋯O(x, 1 + y, z) 2.836 (2) Å, O-H⋯O 133 (2)°; secondary hydroxyl O⋯O({1\over 2} + x, {3\over 2} − y, 1 − z) 2.751 (2) Å, O-H⋯O 174 (2)°].