title: Organocatalytic hetero [4+2] cycloaddition reactions of 2-(1-alkynyl)-2-alkene-1-ones: metal-free access to highly substituted 4H-pyrans.
abstract: Highly substituted 4H-pyrans can be smoothly synthesized from readily available 2-(1-alkynyl)-2-alkene-1-ones by DBU- or n-Bu(3)P catalyzed hetero-[4+2] cycloaddition reactions, in which 2-(1-alkynyl)-2-alkene-1-ones act as both heterodiene and heterodinenophile.
authors.affiliation: Shanghai Key Laboratory of Green Chemistry and Chemical Processes, Department of Chemistry, East China Normal University, 3663 N, Zhongshan Road, Shanghai 200062, PR China.
authors.forename: Xiuzhao
authors.initials: X
authors.lastname: Yu
authors.forename: Zhongyan
authors.initials: Z
authors.lastname: Cao
authors.forename: Junliang
authors.initials: J
authors.lastname: Zhang
mesh_terms: D000475:Alkenes / Q000737:chemistry*; D002384:Catalysis; D003500:Cyclization; D008670:Metals / Q000737:chemistry*; D008956:Models, Chemical; D008968:Molecular Conformation; D011714:Pyrans / Q000737:chemistry*
chemical_list: D000475:Alkenes; D008670:Metals; D011714:Pyrans