The paper reviewed the 13 CNMR features of natural taxane diterpenoids according to their carbonskeleton types. In the 13 CNMR it is easy to distinguish the 6/8/6 and 5/7/6 membered rings by observation of the 13 CNMR...The paper reviewed the 13 CNMR features of natural taxane diterpenoids according to their carbonskeleton types. In the 13 CNMR it is easy to distinguish the 6/8/6 and 5/7/6 membered rings by observation of the 13 CNMR data of C1 and C15. The remarkable differences of the resonance of C13 and C12 were found. In addition, based on various chemical environments many obscured chemical shifts of carbons can be distinguished, such as the oxygenated tertiary carbons of C2, C5, C7, C9 and C13, and sometimes between C9 and C10, as well as between aliphatic quaternary carbons of C8 and C15, and secondary carbons of C6 and C14. All the abovementioned characteristics are helpful for structural elucidation and assignments of the carbon signals of taxoids.展开更多
7-epi-Taxane has been achieved efficiently in gram scale from natural taxane via inversion of the 7-hydroxyl group simply using Ag20 as catalyst and DMF as solvent. The catalyst could he quantitatively recovered by fi...7-epi-Taxane has been achieved efficiently in gram scale from natural taxane via inversion of the 7-hydroxyl group simply using Ag20 as catalyst and DMF as solvent. The catalyst could he quantitatively recovered by filtra- tion without loss of catalytic activity. This condition is also applicable to the direct epimerization of taxane derivatives （e.g., docetaxel and paclitaxel） to 7-epi-taxane derivatives （e.g., 7-epi-docetaxel and 7-epi-paclitaxel）. Furthermore, 33 ester derivatives of 7-epi-taxane with different amino acid moieties at the position of C-13 were successfully synthesized via esterification without protecting C-7-OH. Bioassay results revealed that compounds 13 and 18 have good selectivity against prostatic cancer cell line DU145, with ICs0 value as low as 15.9 nmol/L for 18.展开更多
Two new baccatin Ⅲ type taxoids, 13-Cinnamoylbaccatin Ⅲ (1) and 7-xylosylbaccatin Ⅲ(2), have been isolated from the barks of Taxus yunnanensis. The structures were elucidated by spectral means.
文摘The paper reviewed the 13 CNMR features of natural taxane diterpenoids according to their carbonskeleton types. In the 13 CNMR it is easy to distinguish the 6/8/6 and 5/7/6 membered rings by observation of the 13 CNMR data of C1 and C15. The remarkable differences of the resonance of C13 and C12 were found. In addition, based on various chemical environments many obscured chemical shifts of carbons can be distinguished, such as the oxygenated tertiary carbons of C2, C5, C7, C9 and C13, and sometimes between C9 and C10, as well as between aliphatic quaternary carbons of C8 and C15, and secondary carbons of C6 and C14. All the abovementioned characteristics are helpful for structural elucidation and assignments of the carbon signals of taxoids.
文摘7-epi-Taxane has been achieved efficiently in gram scale from natural taxane via inversion of the 7-hydroxyl group simply using Ag20 as catalyst and DMF as solvent. The catalyst could he quantitatively recovered by filtra- tion without loss of catalytic activity. This condition is also applicable to the direct epimerization of taxane derivatives （e.g., docetaxel and paclitaxel） to 7-epi-taxane derivatives （e.g., 7-epi-docetaxel and 7-epi-paclitaxel）. Furthermore, 33 ester derivatives of 7-epi-taxane with different amino acid moieties at the position of C-13 were successfully synthesized via esterification without protecting C-7-OH. Bioassay results revealed that compounds 13 and 18 have good selectivity against prostatic cancer cell line DU145, with ICs0 value as low as 15.9 nmol/L for 18.
文摘Two new baccatin Ⅲ type taxoids, 13-Cinnamoylbaccatin Ⅲ (1) and 7-xylosylbaccatin Ⅲ(2), have been isolated from the barks of Taxus yunnanensis. The structures were elucidated by spectral means.
