Crystal structures of (3S*,4S*,5S*,6S*)-3,4-epoxy-1,7-dioxaspiro[5.5]undecan-5-ol, (3R*,5S*,6S*)-1,7-dioxaspiro[5.5]undecane-3,5-diyl diacetate and(4S*,5S*6S*)-1,7-dioxaspiro[5.5]undecane-4,5-diol

The structures of (3S*,4S*,5S*,6S*)-3,4-epoxy-1,7-dioxaspiro[5.5]undecan-5-ol (2), (3R*,55*,6S*)-1,7-dioxaspiro[5.5]undecane-3,5-diyl diacetate (4) and (45*,5S*,6S*)-1,7-dioxaspiro[5.5]undecane-4,5-diol (5) have been determined by X-ray crystallography. The unsubstituted tetrahydropyran ring in (2) adopts an axial position with respect to the epoxy-substituted ring and the hydroxy group at C5 is syn to the epoxide group. Intermolecular hydrogen bonding is observed between the C5 hydroxy group and O1. The two six-membered rings in (4) adopt chair conformations and the two acetate groups adopt 1,3-diaxial positions. The C5 hydroxy group in (5) assumes an axial position anti to the C-O bond of the neighbouring ring whilst 4-OH occupies an equatorial position. Intermolecular hydrogen bonding is also observed between 4-OH and 5-OH. Compound (2), C9H14O4, M 186.21, crystallized in the monoclinic space group P 2(1)/c with a 7.867(1), b 12.2060(9), c 9.3676(8) Angstrom, beta 102.744(8)degrees, V 877.4(1) Angstrom(3) and N-o 1163 [I > 2.5 sigma(I)], R 0.031, Rw 0.035. Compound (4), C13H20O6, M 272.30, crystallized in the triclinic space group <P(1)over bar> with a 9.902(1), b 11.0024(9), c 6.9183(5) Angstrom, alpha 104.078(8), beta 96.769(9), gamma 101.980(8)degrees, V 703.8(1) Angstrom(3) N-o 1657 [I > 2.5 sigma(1)], R 0.047, Rw 0.044. Compound (5), C9H16O4, M 188.22, crystallized in he orthorhombic space group Pbca with a 25.504(3), b 8.909(2), c 8.038(2) Angstrom, V 1826.4(5) Angstrom(3), N-o 1096 [I > 2.5 sigma(1)], R 0.030, Rw 0.030.