ABSTRACT
Trinorlabdane 1,5-diketones (7, 10a,b, 13a,b), which are easily prepared from labdane diterpenes, are directly converted into the corresponding 7-oxo-13-hydroxy-8,11,13-podocarpatrienes, immediate precursors of bioactive compounds, under basic treatment. Utilizing this strategy, the first enantiospecific synthesis of 13-hydroxy-8,11,13-podocarpatriene (20), a constituent of Taiwania cryptomerioides, was achieved starting from (-)-sclareol (5) after a seven-step sequence in 55% overall yield.
Subject(s)
Abietanes/chemistry , Diterpenes/chemical synthesis , Abietanes/classification , Catalysis , Diterpenes/classification , Ketones/chemical synthesis , Ketones/chemistry , Molecular Structure , Plants, Medicinal/chemistryABSTRACT
Salvidorol (1), a irregular nor-abietane-type diterpene, was isolated from the aerial parts of Salvia dorrii, in addition to two epimeric abietane diterpenes (2 and 3). This is the first report of a nor-diterpene with an irregular skeleton. The structures were established by high-field NMR techniques ((1)H-(1)H COSY, DEPT, HMQC, HMBC, NOESY and HRMS) and in case of 2 was confirmed by X-ray analysis.