Systematic structural modification of a pentacyclic helical tubuland host diol

Reaction of methylmagnesium chloride and pentacyclo[7.3.0.0(2,7).0(3,11).0(6,10)]dodecane-8,12-dione (4) yields the C-2-symmetric diol (5) (62%) and the unsymmetrical diol (6) (36%) whose crystal structures are analysed in crystal engineering terms. The former isomer is the tenth member of the helical tubuland diol family, crystallizing in space group P3(1)21 as a microporous lattice containing empty parallel canals with 9.9 Angstrom(2) cross-sectional area. Molecules of diol (6) hydrogen bond through (-O-H)(4) cycles to form layers which stack in space group P2(1)/c by means of hydrocarbon dispersion forces. Diol (7), the bis(trifluoromethyl) analogue of (5), does not form a helical tubuland lattice. The structure of its hemihydrate also contains (-O-H)(4) cycles but here the second diol hydroxy group hydrogen bonds to water resulting in a network structure in space group P(4) over bar2$(1)c.