Structure of sp-9-hydroxy-9-pivaloylfluorene, product of base-catalyzed autoxidation of ap-9-pivaloylfluorene

1-(9-Hydroxyfluoren-9-yl)-2,2-dimethyl-1-propanone, C18H18O2, M(r) = 266.34, orthorhombic, Pbcn, a = 18.917 (10), b = 11.843 (8), c = 13.177 (7) A, V = 2952 (5) A3, Z = 8, Dx = 1.198 g cm-3, lambda(Mo K alpha) = 0.71069 A, mu = 0.72 cm-1, F(000) = 1136, T = 296 K, R = 0.044 for 1042 unique observed reflections. Conversion of ap-9-pivaloylfluorene, ap-(I), into lithiated (I)-9-anion followed by the addition of MeOH, then H2O, led to unexpected hydroxylation to provide 20-40% of sp-9-hydroxy-9-pivaloyfluorene, sp-(II), and 60-80% recovery of ap-(I). The singular sp conformation of (II) in solution suggested by NMR was confirmed in the crystalline state by X-ray diffraction which showed the O(1)-C(9)-C(10)-O(2) torsion angle approximately 0 degrees and the C(10) = O(2)...H(9)-O(1) non-bonding distance 1.95 (4) A, suggesting strong intramolecular hydrogen bonding in this conformation.