title: A facile access to polyfunctional oxygen-containing heterocycles via intramolecularly formed protic oxonium ylide trapping processes.
abstract: Based on the assumption that intramolecularly formed protic oxonium ylides could be trapped by electrophiles, transition-metal-catalyzed reactions of diazoesters bearing a primary hydroxy group with electron-deficient aldehydes and isatins were examined. Good to high chemo- and diastereoselectivities were achieved with reactions catalyzed by Cu(hfacac)2. The reactions were assumed to occur via tandem intramolecular protic oxonium ylide formation and subsequent aldol-type addition. They not only provided an efficient entry to 3-substituted 1,4-dioxan-2-one heterocycles with at least one quaternary carbon center but also provided experimental evidence for a stepwise pathway for the transition-metal-catalyzed intramolecular O-H insertion of diazo compounds.
authors.affiliation: Shanghai Engineering Research Center of Molecular Therapeutics and New Drug Development, East China Normal University, Shanghai 200062 (China).
authors.forename: Xin
authors.initials: X
authors.lastname: Guo
authors.forename: Wei
authors.initials: W
authors.lastname: Liu
authors.forename: Wenhao
authors.initials: W
authors.lastname: Hu
mesh_terms: D003500:Cyclization; D006571:Heterocyclic Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D008958:Models, Molecular; D015394:Molecular Structure; D009861:Onium Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D010100:Oxygen / Q000737:chemistry*
chemical_list: D006571:Heterocyclic Compounds; D009861:Onium Compounds; D010100:Oxygen
keywords: aldol-type reaction; heterocycles; quaternary carbon; tandem reactions; ylides