Crystal structures of (±)-1,4-di-O-benzoyl-2,3-O-isopropylidene-myo-inositol and (±)-1,4-di-O-benzoyl-5,6-O-isopropylidene-myo-inositol: a conformational analysis

(±)-1,4-Di-O-benzoyl-2,3-O-isopropylidene-myo-inositol (1) crystallises in the triclinic space group, P1 with unit-cell dimensions a = 10.432(2), b = 11.595(4), c = 12.654(2) Å, α = 67.72(3), β = 11.595(4), γ = 12.654(2) degrees. (±)-1,4-O-Dibenzoyl-5,6-O-isopropylidene-myo-inositol (2) crystallises in the monoclinic space group, P21/n with unit-cell dimensions a = 9.101(2), b = 10.4900(9), c = 22.806(4) Å, α = 90, β = 95.452(10), γ = 90 degrees. The inositol ring of cis-acetal 1 is flattened, whereas that of trans-acetal 2 is more puckered compared to myo-inositol. The acyl migration rates are discussed in terms of the crystalline conformations of 1 and 2.