title: Cooperative catalysis of N-heterocyclic carbene and Brønsted acid for a highly enantioselective route to unprotected spiro-indoline-pyrans.
abstract: A chiral cooperative catalysis of NHC and Brønsted acid for a formal [4+2] reaction of unprotected isatins and enals was developed for the direct synthesis of unprotected spiro[indoline-3,2'-pyran]-2,6'(3'H)-diones in good to excellent yields (up to 95%) with high enantioselectivities (up to >93% ee).
authors.affiliation: College of Materials, Chemistry and Chemical Engineering, Hangzhou Normal University, Hangzhou 310018, China. myang@hznu.edu.cn zgf@hznu.edu.cn.
authors.forename: Youqiang
authors.initials: Y
authors.lastname: Lin
authors.forename: Limin
authors.initials: L
authors.lastname: Yang
authors.forename: Yue
authors.initials: Y
authors.lastname: Deng
authors.forename: Guofu
authors.initials: G
authors.lastname: Zhong
mesh_terms: D007211:Indoles / Q000737:chemistry*; D008697:Methane / Q000031:analogs & derivatives* / Q000737:chemistry; D010421:Pentanoic Acids / Q000737:chemistry; D011714:Pyrans / Q000737:chemistry*; D013141:Spiro Compounds / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D007211:Indoles; D010421:Pentanoic Acids; D011714:Pyrans; D013141:Spiro Compounds; C030011:carbene; C005566:pivalic acid; D008697:Methane