oxygen; 2,4,6-tris(p-chlorophenyl)pyrylium perchlorate in dichloromethane 3 h; Irradiation;

1: 1.) Mg / 1.) ether 2.) ether, 2 h, reflux 2: 74 percent / HgO, BF3*(C2H5)2O / H2O; tetrahydrofuran / 0.25 h / Ambient temperature View Scheme