title: PPh3-catalyzed (3 + 3) annulations of 5-acetoxypenta-2,3-dienoate with 1C,3O-bisnucleophiles: facile entry to stable monocyclic 2H-pyrans.
abstract: Phosphine-catalyzed (3 + 2) and (3 + 3) annulations between 5-acetoxypenta-2,3-dienoate and 1C,3O-bisnucleophiles are presented. The former cases can be achieved with the assistance of base while the latter is dominant without any additive. A series of deuterium-labeling experiments disclosed that the divergence in annulations is likely determined by the involved proton transfer processes.
authors.affiliation: Key Laboratory for Advanced Materials and Institute of Fine Chemicals, East China University of Science and Technology, Meilong Road No. 130, Shanghai, 200237, P. R. China.
authors.forename: Jian
authors.initials: J
authors.lastname: Hu
authors.forename: Wei
authors.initials: W
authors.lastname: Dong
authors.forename: Xin-Yan
authors.initials: XY
authors.lastname: Wu
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Tong