Pyranonaphthoquinone derivatives were synthesized from 1,4-naphthoquinone in three steps. In the first step, 3-phenoxymethyl-1,4-naphthoquinone was synthesized by reacting phenoxy acetic acid with (NH4)2S2O8 and AgNO3 as catalysts. In the next step, 2-acylmethyl-3-phenoxymethyl-1,4-naphthoquinone was synthesized. Finally, 2-acylmethyl-3-phenoxymethyl-1,4-naphthoquinone was subjected to intramolecular cyclization with trimethylamine as the catalyst. This article discusses the mechanism involved in synthesizing pyranonaphthoquinone through the above three stages.