1H-Naphtho[2,3-c]pyran-5,10-dione derivatives, including a natural product (pentalongin), were generally synthesized in one-pot using a tandem conjugate addition-cyclization sequence between 2-(1-hydroxyalkyl)-1,4-naphthoquinones and enamines (or imines). The utility of this method was demonstrated in the synthesis of pyranonaphthoquinone antibiotics, (±)-eleutherin and (±)-isoeleutherin.