Tertiary Amine-Catalyzed (4 + 2) Annulations of δ-Acetoxy Allenoates: Synthesis of Multisubstituted 4<i>H</i>-Pyran and 4<i>H</i>-Chromene
作者:Yiting Gu、Falin Li、Pengfei Hu、Daohua Liao、Xiaofeng Tong
DOI:10.1021/acs.orglett.5b00359
日期:2015.3.6
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
据报道,DABCO催化了δ-乙酰氧基烯丙基酯1的发散(4 + 2)环。发现在DABCO催化剂下1的化学行为与底物有关。具有δC芳族基团的脲基甲酸酯1与水杨醛衍生物2优先反应,生成4 H-色烯3。另一方面,在δC处具有烷基的脲基甲酸酯1易于与氧代二烯4进行(4 + 2)环合,得到4 H-吡喃5。