Crystal and molecular structure of a new diterpenyl glycoside from Pteris cretica L.

The crystal and molecular structure of a new diterpenyl glycoside, Ptr-1, is presented. The crystal is triclinic, space group P1, with a = 8.2414(8) A, b = 13.0826(9) A, c = 6.1427(8) A, α = 95.345(9)°, β = 111.589(8)°, γ = 96.726(7)°, V = 604.9(1) A3, Z = 1. The structure was solved by direct methods and refined by full-matrix least-squares methods to a final R = 0.049 (Rw = 0.099) for 1872 independent reflections. The molecular structure is based on a glycopyranosyl group and a tetracyclic group. The glycopyranosyl group is β-D-allopyranosyl group. The tetracyclic group consists of 1 five-membered and 3 six-membered rings.