Microbial trdrisformation of taxoids was inveStigared: taxoid 2 was transformed into 1β and 14β hydroxylated derivahves 3 and 4, unnatural taxoid 6 was transformed into 1β-hydroxy derivative 7 and 11(15-1) abeotaxa...Microbial trdrisformation of taxoids was inveStigared: taxoid 2 was transformed into 1β and 14β hydroxylated derivahves 3 and 4, unnatural taxoid 6 was transformed into 1β-hydroxy derivative 7 and 11(15-1) abeotaxane 8. Taxoids with an oxetane ring, 11-13 were synthesized from 1 via chemical reachons.展开更多
-An oxetane ring can be constructed from 5 α-acyloxy-Δ4(20) -taxoids with osmylation as the first step in the usual manner. The innovation reported here is the use of an intramolecularly available acyl group for the...-An oxetane ring can be constructed from 5 α-acyloxy-Δ4(20) -taxoids with osmylation as the first step in the usual manner. The innovation reported here is the use of an intramolecularly available acyl group for the protection of 20-OH by an unexpected 5-to 20-migration under slightly basic conditions.展开更多
An oxetane ring can be constructed from 5α-acyloxy-Δ4(20)-taxoids. Hie facile intramolecular acyl migration from 5- to 20-position under slightly basic conditions enabled the construction of the oxetane ring in a co...An oxetane ring can be constructed from 5α-acyloxy-Δ4(20)-taxoids. Hie facile intramolecular acyl migration from 5- to 20-position under slightly basic conditions enabled the construction of the oxetane ring in a convenient short cut, whereas the acyl migration from 2- to 20-position left the 2-hydroxyl accessible to a later benzoylation. An unexpected five-mem-bered 4-O, 20- O sulfite ring was formed in the attempted construction of the oxetane ring with 5α-triflate as a leaving group. After the construction of the oxetane ring, treatment with strong base LiHMDS and acetyl chloride gave the expected 4-O-acetate while treatment with acetic anhydride and DMAP gave a 4-O-acetoacetate.展开更多
New D-seco-taxoids were synthesized from 1-deoxybaccatinⅥand their structures were confirmed by 1H NMR,13C NMR, ESIMS and X-ray crystallography.The key step of the synthesis involved the opening of the oxetane ring u...New D-seco-taxoids were synthesized from 1-deoxybaccatinⅥand their structures were confirmed by 1H NMR,13C NMR, ESIMS and X-ray crystallography.The key step of the synthesis involved the opening of the oxetane ring under acid and basic conditions in order to obtain new multidrug resistance（MDR） reversal agents and new synthetic precursors of paclitaxel analogues.展开更多
文摘Microbial trdrisformation of taxoids was inveStigared: taxoid 2 was transformed into 1β and 14β hydroxylated derivahves 3 and 4, unnatural taxoid 6 was transformed into 1β-hydroxy derivative 7 and 11(15-1) abeotaxane 8. Taxoids with an oxetane ring, 11-13 were synthesized from 1 via chemical reachons.
文摘-An oxetane ring can be constructed from 5 α-acyloxy-Δ4(20) -taxoids with osmylation as the first step in the usual manner. The innovation reported here is the use of an intramolecularly available acyl group for the protection of 20-OH by an unexpected 5-to 20-migration under slightly basic conditions.
基金Project supported by Chinese Academy of Medical Science Researeh Grant and Taisho Pharmaceutical Co. Ltd.
文摘An oxetane ring can be constructed from 5α-acyloxy-Δ4(20)-taxoids. Hie facile intramolecular acyl migration from 5- to 20-position under slightly basic conditions enabled the construction of the oxetane ring in a convenient short cut, whereas the acyl migration from 2- to 20-position left the 2-hydroxyl accessible to a later benzoylation. An unexpected five-mem-bered 4-O, 20- O sulfite ring was formed in the attempted construction of the oxetane ring with 5α-triflate as a leaving group. After the construction of the oxetane ring, treatment with strong base LiHMDS and acetyl chloride gave the expected 4-O-acetate while treatment with acetic anhydride and DMAP gave a 4-O-acetoacetate.
基金the National Natural Science Foundation of China(No.30672506)Leading Academic Discipline Project of Shanghai Municipal Education Commission(No.J50102)
文摘New D-seco-taxoids were synthesized from 1-deoxybaccatinⅥand their structures were confirmed by 1H NMR,13C NMR, ESIMS and X-ray crystallography.The key step of the synthesis involved the opening of the oxetane ring under acid and basic conditions in order to obtain new multidrug resistance（MDR） reversal agents and new synthetic precursors of paclitaxel analogues.
