Synthesis of 5‐/10‐Membered Ring Analogues of the Dienediyne Core of Neocarzinostatine Chromophore by Palladium(0)‐Mediated Ring‐Closure Reaction

Abstract

Abstract The new dienediynes 5 , 6 , and 7 were synthesised from a monoprotected diyne and an already described bis(enol triflate) 4 derived from formylcyclopentanone. When 5 and 6 were subjected to nucleophilic attack by a thiol, cycloaromatisation occurred, and the phenanthrenes 23a and 23b were obtained in 30 and 42% yield, respectively.