An attempted synthesis of the 5,6-Dihydrocyclobuta[l]phenanthrene system by a Thorpe cyclization

Abstract

Methyl 10-cyanomethylphenanthrene-9-carboxylate (1e) has been subjected to conditions known to favour Thorpe cyclization, but the desired 5,6- dihydrocyclobuta[l]phenanthrene system (3) was not obtained. An alternative cyclization to give 3-ethoxydibenzo[f,h]isoquinolin-1(2H)- one (4) occurs.