Crystal structure of the diterpene tinophyllone

Abstract

The diterpene tinophyllone, C₂₁H₂₄O₆, crystallises in space group P2₁ with Z= 2 and cell parameters a= 6·852, b= 15·09, c= 9·523 Å, β= 105·2°. A computer application of the tangent formula of Karle and Hauptman was used to solve the structure as 15,16-epoxy-19-methoxycarbonyl-2-oxo-5α-celeroda-3,13(16), 14-trien-17,12S-olide (III). The absolute configuration is assigned from consideration of o.r.d. data concerning 3,4-dihydrotinophyllone (V). Least squares refinement with anisotropic thermal parameters for the non-hydrogen atoms gave an R of 0·053 for 1451 non-zero diffractometer data. All hydrogen atoms were located from a difference map. Standard deviations of non-hydrogen distances and angles average 0·007 Å and 0·4° respectively. The analysis shows that rings A and B of tinophyllone which are cis-fused are present in the chair conformations. Ring C, which is trans-fused to ring B, is present in a boat conformation.