Structure of (±)-(1R,6S)-1-benzyloxy-8,11,11-trimethyl-6-phenylthiobicyclo[5.3.1]undec-7-en-3-one

C27H32O2S, Mr = 420.61, monoclinic, P2(1)/c, a = 8.4756(13), b = 14.710(2), c = 18.425(3) A, beta = 99.575(13) degrees, V = 2265.2(6) A3, Z = 4, Dx = 1.23 g cm-3, mu = 1.5567 cm-1, Mo K alpha, lambda = 0.7107 A, F(000) = 904, T = 298 K, R = 0.0630 for 2942 reflections [Fo greater than or equal to 6 sigma (Fo)]. The cyclooctane portion of the [5.3.1] ring system assumes the boat-chair conformation while the cyclohexene portion has the boat conformation. As has been observed in other [5.3.1]undecene systems, ring strain appears to cause a distortion of the geometry of the bridgehead alkene. The bond length C7--C8 [1.343(5) A] is long for an isolated C--C double bond. The Csp2--Csp3 bond lengths at C7 are asymmetric with C7--C6 being 1.498(5) A while C7--C11 is 1.535(5) A. The maximum deviation from ideality for the torsion angles around the double bond is 16.2(4) degrees (absolute value). This twist in the alkene group is reflected in the non-planarity of the group [max. deviation 0.193(6) A for C9] and in the dihedral angle between the nearly planar portions (C6, C7, C8, C11 and C7, C8, C9, C15), which is 9.4(2) degrees.