1,5,7,11-Tetraoxaspiro[5.5]undecane, 3,9-dimethylidene-1,5,7,11-tetraoxaspiro[5.5]undecane and 1,5-dioxa-7,11-dithiaspiro[5.5]undecane
MK Bromley, MG Looney, DH Solomon, RW Gable, M Helliwell, P Hodge
ACTA CRYSTALLOGRAPHICA SECTION C-CRYSTAL STRUCTURE COMMUNICATIONS | MUNKSGAARD INT PUBL LTD | Published : 1998
In all three title compounds, C7H12O4, (1), C9H12O4, (2), and C7H12O2S2, (3), the spiro C-O distances are substantially shorter than the non-spiro C-O distances as a result of the anomeric effect. In contrast, the spiro C-S distances of compound (3) are similar to the non-spiro C-S distances. In all three compounds, steric repulsions between the lone pairs on the O or S atoms and the axial H atoms of the opposite ring result in a distorted geometry around the spiro-C atoms.