title: Synthesis of the aglycon of aspafiliosides E and F based on cascade reactions.
abstract: A synthesis of C17α-OH-tigogenin, the aglycon of aspafiliosides E and F, is described. The main features of the synthesis are three cascade processes, which involve the iodo-lactonization of furostan-26-acid to open ring E, a cascade hydrolysis/intramolecular SN2 process to close ring E, and a cascade intramolecular redox-ketalization process to close ring F. This synthesis would enrich the strategies used for the manipulation of spiroketals in steroidal sapogenins and other substrates.
authors.affiliation: The Key Laboratory of Synthetic Chemistry of Natural Substances, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China. shiong81@sioc.ac.cn wstian@sioc.ac.cn.
authors.forename: Jing-Jing
authors.initials: JJ
authors.lastname: Wu
authors.affiliation: The Key Laboratory of Synthetic Chemistry of Natural Substances, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China. shiong81@sioc.ac.cn wstian@sioc.ac.cn.
authors.forename: Yong
authors.initials: Y
authors.lastname: Shi
authors.affiliation: The Key Laboratory of Synthetic Chemistry of Natural Substances, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China. shiong81@sioc.ac.cn wstian@sioc.ac.cn.
authors.forename: Wei-Sheng
authors.initials: WS
authors.lastname: Tian
mesh_terms: D006868:Hydrolysis; D008958:Models, Molecular; D012503:Saponins / Q000138:chemical synthesis*
chemical_list: D012503:Saponins; C528191:aspafilioside E; C528192:aspafilioside F