Jan-Eric Berg

Eight new cembranoids from tobacco - structural elucidation and conformational studies ☆

Abstract Eight new cembranoids have been isolated from an extract of flowers of Greek tobacco. They have been identified as (1S,2E,4S,R,7E,10R,11E)-2,7,11-cembratriene-4,6,10-triol (1), the corresponding (10S)-, (4R*)- and (4R*,10S*)-diastereomers (2–4), (1S*,2E,4R*,6R*,7E,10S*,11Z)-2,7,11-cembratriene-4,6,10-triol (5), (1S,2E,4S,6R,7E,11E)-4,6-dihydroxy-2,7,11-cembratrien-10-one (6), the corresponding (4R*)-epimer (7) and (1S*,2E,4S*,7E,10S,11E)-4,10-dihydroxy-2,7,11-cembratrien-6-one (8) with the aid of chemical and spectral methods, 2D-NMR techniques being particularly helpful. The crystal structure of the diacetate 11 has been determined and is described. The solution conformations of triols 1 and 3 have been studied by using NMR methods in conjunction with molecular mechanics calculations (MM3). The biogenesis of the new compounds is discussed.

7,8-epoxy-4-basmen-6-one, a tobacco diterpenoid having a novel skeleton, having a novel skeleton

Abstract A dieterpenoid, probably cembrane-derived and having an novel skeleton, has been isolated from Greek tobacco. Its structure has been determined by spectroscopic methods and X-ray analysis.

Conformational analysis of a 7,8-epoxycembranoid

Abstract An analysis of the solution conformation of (1S,2E,4S,6R,7R,8R,11E)-7,8-epoxy-2,11-cembradiene-4,6-diol (1), a tobacco diterpenoid, has been performed by using NMR methods, molecular mechanics calculations and molecular dynamics simulations, and the solid state structure has been determined by X-ray analysis. The results obtained indicate that the solid state structure is essentially retained in solution.