title: Organocatalytic asymmetric cascade reactions of 7-vinylindoles: diastereo- and enantioselective synthesis of C7-functionalized indoles.
abstract: The first catalytic asymmetric cascade reaction of 7-vinylindoles has been established by the rational design of such substrates. Cascade reactions with isatin-derived 3-indolylmethanols in the presence of a chiral phosphoric acid derivative allow the diastereo- and enantioselective synthesis of C7-functionalized indoles as well as the construction of cyclopenta[b]indole and spirooxindole frameworks (all >95:5 d.r., 94->99 % ee). This approach not only addresses the great challenge of the catalytic asymmetric synthesis of C7-functionalized indoles, but also provides an efficient method for constructing biologically important cyclopenta[b]indole and spirooxindole scaffolds with excellent optical purity. Investigation of the reaction pathway and activation mode has suggested that this cascade reaction proceeds through a vinylogous Michael addition/Friedel-Crafts process, in which dual H-bonding activation of the two reactants plays a crucial role.
authors.affiliation: School of Chemistry and Chemical Engineering, Jiangsu Normal University, Xuzhou, 221116 (China). fshi@jsnu.edu.cn.
authors.forename: Feng
authors.initials: F
authors.lastname: Shi
authors.forename: Hong-Hao
authors.initials: HH
authors.lastname: Zhang
authors.forename: Xiao-Xue
authors.initials: XX
authors.lastname: Sun
authors.forename: Jing
authors.initials: J
authors.lastname: Liang
authors.forename: Tao
authors.initials: T
authors.lastname: Fan
authors.forename: Shu-Jiang
authors.initials: SJ
authors.lastname: Tu
keywords: asymmetric synthesis; cascade reactions; organocatalysis; spirooxindole; vinylindoles