Systematic Structural Modification of a Pentacyclic Helical Tubuland Host Diol

Abstract

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 C₂-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 groupP 3₁21 as a microporous lattice containing empty parallel canals with 9· 9Ųcross-sectional area. Molecules of diol (6) hydrogen bond through (-O-H)₄ cycles to form layers which stack in space group P 2₁/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^-42₁c.