title: Tertiary amine-catalyzed (4 + 2) annulations of δ-acetoxy allenoates: synthesis of multisubstituted 4H-pyran and 4H-chromene.
abstract: The DABCO-catalyzed divergent (4 + 2) annulations of δ-acetoxy allenoates 1 are reported. The chemical behavior of 1 under DABCO catalyst was found to be substrate dependent. Allenoate 1 with an aromatic group at δC preferentially reacted with salicylaldehyde derivative 2, delivering 4H-chromenes 3. On the other hand, allenoates 1 with an alkyl group at δC readily underwent (4 + 2) annulations with oxo diene 4 to afford 4H-pyrans 5.
authors.affiliation: Shanghai Key Laboratory of Functional Materials Chemistry, East China University of Science and Technology , Shanghai 200237, China.
authors.forename: Yiting
authors.initials: Y
authors.lastname: Gu
authors.forename: Falin
authors.initials: F
authors.lastname: Li
authors.forename: Pengfei
authors.initials: P
authors.lastname: Hu
authors.forename: Daohua
authors.initials: D
authors.lastname: Liao
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Tong