title: Organocatalytic Asymmetric Synthesis of Dihydrobenzoxazinones Bearing Trifluoromethylated Quaternary Stereocenters.
abstract: Chiral phosphoric acid-catalyzed enantioselective aza-Friedel-Crafts reaction of trifluoromethyl benzoxazinones with pyrroles is reported. Under mild conditions, a range of enantioenriched dihydrobenzoxazinones bearing trifluoromethylated quaternary stereocenters could be obtained in good to excellent yield and ee. A remarkable fluorine effect is observed, and preliminary mechanistic studies combined with theory calculations suggest that triple-hydrogen-bonding interactions hold the transition structure rigidly and allow the bulky substituents of the catalyst to influence the enantioselectivity.
authors.affiliation: Department of Chemistry, Zhejiang University , Hangzhou 310027, P. R. China.
authors.forename: Hengqiao
authors.initials: H
authors.lastname: Lou
authors.affiliation: Department of Chemistry, Zhejiang University , Hangzhou 310027, P. R. China.
authors.forename: Yongtao
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Chemistry, Zhejiang University , Hangzhou 310027, P. R. China.
authors.forename: Enze
authors.initials: E
authors.lastname: Jin
authors.affiliation: Department of Chemistry, Zhejiang University , Hangzhou 310027, P. R. China.
authors.forename: Xufeng
authors.initials: X
authors.lastname: Lin