CONFORMATIONAL-ANALYSIS OF THE 10-HYDROXY AND 13-HYDROXY DERIVATIVES OF CEMBRENE

Conformational analysis of 10- and 13-hydroxycembrenes 4, 5, 7, and 8 has been carried out using NMR methods and molecular mechanics calcula tions. The results indicate that the conformational states of all inve stigated compounds in solution are characterized by the same orientati on of double bonds with respect to the average plane of the macrocycle . Alcohols 4 and 8 are conformationally homogeneous, and their solutio n conformations correspond to the known solution (and crystal) conform ation of cembrene (1). In the case of alcohols 5 and 7, there is addit ional conformational flexibility in the C(8)-C(11) molecular fragment. The influence of simple substituent (hydroxy group) effects and an in tramolecular OH pi-hydrogen bond on conformational states of the cemb ranoids are discussed.