Iron(III) chloride catalyzed oxidative coupling of aromatic nuclei.

Easily available and nontoxic FeCl(3) catalyzes intramolecular oxidative coupling for the direct construction of the phenanthrene ring using meta-chloroperbenzoic acid as sole oxidant at room temperature in excellent yields. The mechanistic investigations show that FeCl(3)-catalyzed coupling proceeds through the heterolytic coupling (A(+) + B). The catalytic approach has been applied to intermolecular biaryl coupling of 2-naphthols and phenol ether.