“…Dimethyl cyclohepta-3,5,7-triene-1,3-dicarboxylate (1) was synthesized according to the literature (Vogel et al, 1980(Vogel et al, , 1986. A CH 2 Cl 2 solution (30 ml) of substituted cycloheptatriene 1 (3 g, 14.42 mmol) and TPP (50 mg, 0.075 mmol) was irradiated with a projector lamp (500 W), while a slow stream of dry O 2 was passed through it continuously.…”