Homo-Diels–Alder cycloadditions catalysed by cobalt–triphenylphosphine-zinc systems

Abstract

[Col2(PPh3)n]–zinc systems (n=1 or 2) exhibit high catalytic activity for the homo-Diels–Alder [2 + 2 + 2] cycloadditions of norbornadiene with various alkynes including terminal and internal acetylenes and methyl prop-2-ynyl ether to give the corresponding deltacyclenes in good to excellent yields.