title: Enantioselective Synthesis of Spiro[cyclohexane-1,3'-indolin]-2'-ones Containing Multiple Stereocenters via Organocatalytic Michael/Aldol Cascade Reactions.
abstract: Organocatalytic reactions of 3-olefinic oxindoles and pentane-1,5-dial were investigated to provide access to substituted spirocyclohexane oxindoles via Michael/Aldol cascade reactions. Of particular interest, we have examined the stereochemical outcome of electron withdrawing and electron-donating groups on the oxindole ring nitrogen. Interestingly, we have observed that theN-protecting group on the oxindole has critical effect on aldol ring closure leading to ultimate stereochemical outcome of the hydroxyl center. The overall process is quite efficient and afforded products with multiple stereocenters in high yields and excellent enantioselectivities (>99%ee).
authors.affiliation: Departments of Chemistry and Medicinal Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States.
authors.forename: Arun K
authors.initials: AK
authors.lastname: Ghosh
authors.affiliation: Departments of Chemistry and Medicinal Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States.
authors.forename: Bing
authors.initials: B
authors.lastname: Zhou
keywords: Aldol reaction; Asymmetric catalysis; Michael reaction; Organocatalyst; Spiroindole