title: Divergent NHC-catalyzed oxidative transformations of 3-bromoenal: selective synthesis of 2H-pyran-2-ones and chiral dihydropyranones.
abstract: A selective synthesis of either 2H-pyran-2-ones (4) or chiral dihydropyranones (6) from the same substrates of 3-bromoenals and 1,3-dicarbonyl compounds upon oxidative N-heterocyclic carbene catalysis is presented. It is shown that the oxidative transformation of 3-bromoenals under NHC catalyst can be well controlled to proceed through two pathways, i.e., elimination of reducible β-bromide or by an external oxidant 3, allowing the selective generation two sorts of unsaturated acyl azoliums, respectively.
authors.affiliation: Department of Chemistry, Zhejiang University, 20 Yugu Road, Hangzhou 310027, China.
authors.forename: Gang
authors.initials: G
authors.lastname: Wang
authors.forename: Xia
authors.initials: X
authors.lastname: Chen
authors.forename: Gaohan
authors.initials: G
authors.lastname: Miao
authors.forename: Weijun
authors.initials: W
authors.lastname: Yao
authors.forename: Cheng
authors.initials: C
authors.lastname: Ma