title: N-heterocyclic carbene-catalyzed diastereoselective and enantioselective reaction of 2-aroylvinylcinnamaldehydes with α,β-unsaturated imines: complete control and switch of diastereoselectivity by N-substituents of catalysts.
abstract: Highly diastereoselective and enantioselective reactions between 2-aroylvinylcinnamaldehydes and α,β-unsaturated imines were achieved under asymmetric catalysis of chiral triazole carbene catalysts. In the presence of N-anisylindeno[2,1-b]triazolo[4,3-d][1,4]oxazinium salt, the reaction of 2-aroylvinylcinnamaldehydes with α,β-unsaturated imines afforded indeno[2,1-c]pyran-1-one derivatives 4 with 90%-99% ee, while enantiopure indenocyclopentan-1-ones 5 (>99% ee) were obtained under the catalysis of N-mesitylindeno[2,1-b]triazolo[4,3-d][1,4]oxazinium salt. A slight variation of an N-substituent on triazole carbenes was found to switch completely the diastereoselectivity of the reaction for the formation of indeno[2,1-c]pyran-1-ones.
authors.affiliation: College of Chemistry, Beijing Normal University , Beijing 100875, China.
authors.forename: Zi-Tian
authors.initials: ZT
authors.lastname: Wang
authors.forename: Yuan
authors.initials: Y
authors.lastname: Zhao
authors.forename: Zhan-Yong
authors.initials: ZY
authors.lastname: Wang
authors.forename: Ying
authors.initials: Y
authors.lastname: Cheng