title: Enantioselective synthesis of spiro[indoline-3,4'-pyrano[2,3-c]pyrazole] derivatives via an organocatalytic asymmetric Michael/cyclization cascade reaction.
abstract: An efficient enantioselective synthesis of spiro[indoline-3,4'-pyrano[2,3-c]pyrazole] derivatives by a cascade reaction between pyrazolones and isatylidene malononitriles is described. With only 1 mol% of (DHQD)2PYR, chiral spirooxindole derivatives have been produced in excellent yields (96-99%) with good-to-excellent enantioselectivities (up to 91% ee).
authors.affiliation: Key Laboratory for Advanced Materials and Institute of Fine Chemicals, East China University of Science and Technology, Shanghai 200237, P. R. China. xinyanwu@ecust.edu.cn.
authors.forename: Jin
authors.initials: J
authors.lastname: Xie
authors.forename: Xiao-Yu
authors.initials: XY
authors.lastname: Xing
authors.forename: Feng
authors.initials: F
authors.lastname: Sha
authors.forename: Zhi-Yan
authors.initials: ZY
authors.lastname: Wu
authors.forename: Xin-Yan
authors.initials: XY
authors.lastname: Wu