HYDROXYLATED DITERPENOIDS FROM HALIMIUM-VISCOSUM

Several hydroxylated bi- and tri-cyclic terpenoids have been isolated from the aerial parts of Halimium viscosum (Celorico da Beira, Portuga l). Together with valparolone, with the same skeleton, two additional compounds have been identified: (4S)-2 beta-acetoxyvalparol-15-en-3-on e and (4S)-2 beta-acetoxyvalparol-8(14)-en-3-one. Together with the we ll-known valpara-3(19),15-dien-2 beta-ol, valpara-1,13-dien-2 alpha-ol and 2 beta-acetoxyvalpara-4,15-dien-3 alpha-ol, two new compounds hav e been isolated, belonging to the valparane class, and identified as v alpara-3,15-dien-2 beta-ol and 3 alpha-hydroxyvalpara-4,15-dien-2-one. There are several bicyclic diterpenoids that should be noted: with la bdane skeleton; a diformate and the monoformylderivatives of labd-7-en -3 beta,15-diol and with halimane skeleton the 15-hydroxy-ent-halim-1( 10)-en-18,2 beta-olide. The total composition of the aerial parts of t his plant allows the identification of Celorico da Beira Halimium visc osum as a new chemotype. (C) 1998 Elsevier Science Ltd. All rights res erved.