Nickel-Catalyzed Intermolecular [3 + 2 + 2] Cocyclization of Ethyl Cyclopropylideneacetate and Alkynes
作者:Shinichi Saito、Manami Masuda、Shinsuke Komagawa
DOI:10.1021/ja0494306
日期:2004.9.1
The [3 + 2 + 2] cocyclization of ethylcyclopropylideneacetate (1a) and terminal alkynes (2) proceeded smoothly in the presence of 10 mol % "Ni(PPh3)2", which was prepared in situ from Ni(cod)2 and PPh3. The high reactivity of 1a, which was induced by the introduction of an electron-withdrawing group, is very important for the progress of this reaction. The cycloheptadiene derivatives were synthesized
The [3 + 2 + 2] cocyclization of ethylcyclopropylideneacetate (1a) and various alkynes proceeded smoothly in the presence of Ni(cod)2–PPh3. The cycloheptadiene derivatives were synthesized in highly selective manners. The unique reactivity of 1a was essential for the progress of the reaction. The observed regioselectivity of the product formation and the mechanism of the reaction are discussed.