Novel bicyclic taxane diterpenoids from the needles of Chinese yew, Taxus mairei

An investigation on the constitution of the needles of Chinese yew, Tans mairei, led to the isolation of sixteen novel taxane diterpenoids. The structures of these new compounds were established unambiguously as (3E,8E)-2alpha,7beta,9,10beta, 13alpha 20-hexaacetoxy-5(2'-acetoxy-cinnamoyloxy)-3,8-secotaxa-3,8,11-triene (1), l3-deacetyl canadensene (2), 7-deacetyl canadensene (3), 2alpha,5alpha,7beta,9,10beta,13alpha,20-heptaacetoxy-3,8-secotaxa-3,8,11-triene (5-acetyltaxachitriene A) (4), (3E,7E)-2alpha,5alpha,10beta,13alpha,20-pentaacetoxy-3,8-secotaxa-3,7,11-trien-9-one (5), (3E,7E)-2alpha,10beta,13alpha,20-tetraacetoxy-5alpha-hydroxy-3,8-secotaxa-3,7,11-trien-9-one (6), (3E,7E)-2alpha,5alpha,10beta,13alpha,-tetraacetoxy-20-hydroxy-3,8-secotaxa-3,7,11-trien-9-one (7), (3E,7E)-10beta,13alpha-diacetoxy-2alpha,5alpha,20-trihydroxy-3,8-secotaxa-3,7,11-trien-9-one (8), (3E,7E)-2alpha,10beta,13alpha-triacetoxy-5alpha,20-dihydroxy-3,8-secotaxa-3,7,11-trien-9-one (9), (3E,7E)-2alpha,10beta-diacetoxy-5alpha,13alpha,20-trihydroxy-3,8-secotaxa-3,7,11-trien-9-one (10), (3E,8E)-7beta,9,10beta,13alpha,20-pentaacetoxy-3,8-secotaxa-3,8,11-triene-2alpha,5alpha-diol (11), 5-O-(N,N-dimethyl-3-phenylisoseryl) taxachitriene A (12), (3E,8E)-5alpha-hydroxy1-2alpha,7beta,9,10beta,20-pentaacetoxy-3,8-secotaxa-3,8,11-triene-13-one (13), (3E,8E)-2alpha,5alpha,20-trihydroxy-7beta,9,10beta-triacetoxy-3,8-secotaxa-3,8,11-triene-13-one (14), (3E,8E)-2alpha,9,10beta,13alpha, 20-pentaacetoxy-3,8-secotaxa-3,8,11-triene-5alpha,7beta-diol (15), and (3E,8E)-2alpha,7beta,9,10beta,20-pentaacetoxy-3,8-secotaxa-3,8,11-triene-5alpha,13alpha-diol (16) on the basis of 1D and 2D NMR spectra including 1H NMR, 1H-1H COSY, 13C NMR, DEPT, HMBC, HMQC, ROESY and NOESY, and HR-FAB-MS analyses. In addition, several known bicyclic taxoids were also isolated, and their structures were determined with the aid of spectral data and by comparison with the data described in the literature