Six new taxane diterpenoids from the seeds of taxus chinensis var. mairei and taxus yunnanensis

Six new taxane diterpenoids and three known 2(3-->20)abeotaxoids were isolated from the seeds of Taxus chinensis var. mairei and of Taxus yunnanensis. Their structures were established as 2alpha, 20-dihydroxy-9alpha-acetoxytaxa-4(20),11-dien-13-one (1), 5alpha-cinnamoyloxy-7beta,10beta, 13alpha-triacetoxy-2(3-->20)abeotaxa-2alpha-ol-4(20),11-dien-9-one (2), 5alpha-cinnamoyloxy-10beta, 13alpha-diacetoxy-2(3-->20)abeotaxa-2alpha,7beta-diol-4(20), 11-dien-9-one (3), 5alpha-cinnamoyloxy-2alpha,7beta,10beta, 13alpha-tetraacetoxy-2(3-->20)abeotaxa-4(20),11-dien-9-one (4), 7-O-acetyltaxine A (5), 2alpha,7beta,10beta, 13alpha-tetraacetoxy-5alpha-phenylisoserinatoxy-2(3-->20)abeotaxa-4(2 0),11-dien-9-one (6), 5-O-acetyltaxinine M (7), 5alpha-hydroxy-2alpha,7beta,10beta, 13alpha-tetraacetoxy-2(3-->20)abeotaxa-4(20),11-dien-9-one (8), and 2alpha,5alpha-dihydroxy-7beta,10beta, 13alpha-triacetoxy-2(3-->20)abeotaxa-4(20),11-dien-9-one (9), on the basis of 1D and 2D NMR spectroscopic analysis. Compound 1, as a new compound isolated from T. chinensis var. mairei, is a rare example of a taxane with a 4,11-diene unit, which is considered to be an important intermediate in the biogenesis of taxoids. Compounds 2-4, 6, and 7 are new compounds, isolated from T. yunnanensis, which also afforded the known compounds 5, 8, and 9.