OLIGOMERIZATION OF 3-HEXYNE BY NICKEL(0) COMPLEXES UNDER CO2. INCORPORATION OF CO2 AND NOVEL CYCLOTRIMERIZATION

Abstract

Abstract Tetraethyl-2-pyrone 1 was formed in good yields on the reaction of 3-hexyne with CO2 in the presence of Ni(COD)2–Ph2P(CH2)4PPh2 (COD=1,5-cyclooctadiene), and in case of Ni(COD)2–PPh3 a novel cyclotrimer, pentaethyl-5-propenylcyclopentadiene 2 was obtained selectively.