Asymmetric Synthesis of 4‘-Ethoxy-2‘,3‘-didehydro-2‘,3‘-dideoxynucleosides by Palladium-Catalyzed Kinetic Discrimination between the Corresponding Diastereoisomeric Lactol Acetates
作者:Louis S. Hegedus、Katherine L. Hervert、Satoshi Matsui
DOI:10.1021/jo011074b
日期:2002.6.1
4'-Substituted nucleoside analogues have been synthesized using palladium-catalyzed asymmetric allylic amination conditions. A kinetic discrimination between the diastereomeric lactol acetates (3) produced the desired aminated products (6a-d) and recovered acetate (alpha-3) in high yields and <97:3 diastereoselectivity. Epimerization of the recovered lactol acetate (alpha-3) produced a 60:40 alpha/beta mixture of (3), which could be resubjected, in principle, to the palladium-catalyzed asymmetric allylic amination conditions.
Synthesis of (+)-Neplanocin A from a Chromium−Carbene Complex-Derived Optically Active Butenolide
作者:L. S. Hegedus、L. Geisler
DOI:10.1021/jo000154x
日期:2000.6.1
De Novo Synthesis of 4‘-Ethoxy Nucleoside Analogues
作者:Louis S. Hegedus、Lisa Geisler、Andrew G. Riches、Sarri S. Salman、Gisela Umbricht
DOI:10.1021/jo020151f
日期:2002.11.1
Butenolides 5a and 13 were used as opticallyactive templates in the de novo synthesis of 4'-disubstituted nucleoside analogues. The butenolides were reduced and acylated in situ to give acetates 10 and 14. Vorbrüggen coupling gave the protected nucleoside analogues 11 and 15. Reduction of 11 gave 4'-ethoxy-2',3'-dideoxythymidine (6) and deprotection of 15 gave 4'-ethoxy-2',3'-dideoxydidehydrothymidine