Two new taxane diterpenoids from Taxus mairei

Two new taxane diterpenoids were isolated from the heartwood of Taxus mairei and identified as 5 alpha, 7 beta, 9 alpha, 10 beta, 13 alpha-pentaacetoxy-2 alpha-benzoyloxy-4 alpha, 20-dihydroxytax-11-ene [2] and 7 beta, 9 alpha, 10 beta, 13 alpha, 20-pentaacetoxy-2 alpha-benzoyloxy-4 alpha, 5 alpha-dihydroxytax-11-ene[3]. The structures of 2 and 3 were determined primarily on the basis of analysis of their 1H-nmr, 13C-nmr, 1H-1H 2D COSY, 1H-13C 2D COSY, DEPT, and mass spectra. This is the first report of naturally occurring taxoids lacking a D ring but oxygenated at the 4, 5, and 20 positions.