The structure of a key intermediate in the total synthesis of dendrobine

(1R*,4R*,5S*,8R*,11S*)-3,11-Dimethyl-5-hydroxy-6-isopropyl-3-azatricy clo[6.2.1.0(4,11)]undec-6-en-2-one, C15H23NO2, Mr = 249.35, monoclinic, P2(1)/c, a = 7.782(2), b = 23.119(4), c = 7.932(2) A, beta = 101.53 (2)degrees, V = 1398.1(5) A3, Z = 4, Dx = 1.184 g cm-3, Mo K alpha, gamma = 0.7107 A, mu = 0.7259 cm-1, F(000) = 544, T = 298 K, R = 0.0464 for 1887 reflections (F0 greater than or equal to 4[sigma (F0)]). The molecules are H-bonded into infinite columns parallel to c involving the hydroxyl group and the carbonyl O atom [O15...O13(x,y,z-1) 2.756(2); H15...O13 1.84(3) A; O-H...O 173(3) degrees]. The bonds from the bridgehead atom of the tricyclic ring to other ring atoms appear to be elongated [av. 1.549(2) A] compared to the other Csp3-Csp3 bonds in the molecule.