5,5 0 -Di-tert-butyl-2,2 0 -dihydroxy- 3,3 0 -methanediyldibenzaldehyde and its allyl-protected dialcohol and dialdehyde precursors Sandrine Goetz, Julia Barreira Fontecha and Vickie McKee* Chemistry Department, Loughborough University, Leicestershire LE11 3TU, England Correspondence e-mail: v.mckee@lboro.ac.uk Received 9 August 2004 Accepted 24 August 2004 Online 9 October 2004 5,5 0 -Di-tert-butyl-2,2 0 -dihydroxy-3,3 0 -methanediyldibenzalde- hyde, C 23 H 28 O 4 , (IV), has been structurally characterized in two polymorphic forms. The tetragonal form, (in I4 1 /a) has been reported previously but is redetermined and reinter- preted here, while the monoclinic form, (in C2/c) is reported for the ®rst time. In both polymorphs, the molecule lies on a crystallographic twofold axis. Two precursors in the synthesis of (IV), namely 2,2 0 -bis(allyloxy)-5,5 0 -di-tert-butyl- 3,3 0 -methanediyldibenzenemethanol (C 29 H 40 O 4 ) and 2,2 0 -bis- (allyloxy)-5,5 0 -di-tert-butyl-3,3 0 -methanediyldibenzaldehyde (C 29 H 36 O 4 ) have also been characterized. Comment The diphenolic dialdehyde 5,5 0 -di-tert-butyl-2,2 0 -dihydroxy- 3,3 0 -methanediyldibenzaldehyde, (IV), has been used to synthesize new polynucleating macrocycles by Schiff base condensation with diamines (Barreira Fontecha et al., 2002). Compound (IV) was prepared in three steps from the known dialcohol analogue 5,5 0 -di-tert-butyl-2,2 0 -dihydroxy-3,3 0 -me- thanediyldibenzenemethanol, (I) (Dhawan & Gutsche, 1983). The structure of 2,2 0 -bis(allyloxy)-5,5 0 -di-tert-butyl-3,3 0 - methanediyldibenzenemethanol, (II), is shown in Fig. 1. The molecule is non-planar, with the two aryl rings inclined at 78.84 (9)  with respect to one another and the tert-butyl groups lying on opposite sides of the molecule. The apparent folding of the molecule is actually due to rotation about the C12ÐC4 and C12ÐC13 bonds, and the conformation adopted is probably a consequence of the hydrogen-bonding network throughout the lattice. Hydrogen bonding between alcohol groups generates eight-membered rings [graph-set notation R 4 4 (8)] and links the molecules into a double chain running parallel to the a axis (Fig. 2 and Table 1). The H atoms on the hydroxy groups are disordered, and these atoms were modelled with 50% occupancy of two equivalent positions. As a result there are two self-consistent hydrogen-bonding patterns, which have OÐHO directions running either anticlockwise (as in Fig. 2) or clockwise around the same ring. The highest residual electron-density peak is 1.26 A Ê from atom C28 and 1.39 A Ê from atom C27, and may indicate a minor disorder of that allyl group. The dialcohol was oxidized using MnO 2 to form the analogous dialdehyde, 2,2 0 -bis(allyloxy)-5,5 0 -di-tert-butyl-3,3 0 - methanediyldibenzaldehyde, (III). As Fig. 3 shows, the phenyl planes are inclined at 74.17 (5)  and the tert-butyl groups are on the same side of the molecule. One of the allyl groups is disordered, and this disorder was modelled as a 70:30 occu- pancy of two conformations. Again, the molecules are linked by hydrogen bonding into a double chain, in this case running organic compounds o776 # 2004 International Union of Crystallography DOI: 10.1107/S010827010402089X Acta Cryst. (2004). C60, o776±o780 Acta Crystallographica Section C Crystal Structure Communications ISSN 0108-2701 Figure 1 A view of the structure of (II). The H atoms on the two alcohol functions are disordered and only one position is shown for each. Displacement ellipsoids are drawn at the 50% probability level.