NUCLEOPHILIC SUBSTITUTIONS OF 2-HALONAPHTHO[2,3-B]FURAN-4,9-DIONES AND 2-NITRONAPHTHO[2,3-B]FURAN-4,9-DIONE

2-Chloronaphtho[2,3-b]furan-4,9-dione (4) was allowed to react with so dium phenoxide to produce 2-phenoxynaphtho[2,3-b]furan-4,9-dione (8) i n 55% yield. Also, in a similar manner, 8 was obtained from the reacti ons of 2-bromonaphtho[2,3-b]furan-4,9-dione (5), 2-iodonaphtho[2,3-b]f uran-4,9-dione (6) and 2-nitronaphtho[2,3-b]furan-4,9-dione (7) with s odium phenoxide. The reaction of 4 with sodium methoxide gave methyl 3 -hydroxy-1,4-naphthoquinone-2-acetate (9) in which the furan ring was cleaved. 2-Phenylthionaphtho[2,3-b]furan-4,9-dione (11) and 2-methylth ionaphtho[2,3-b]furan-4,9-dione (12) were obtained from the reactions of 4 with thiolates in 63% and 62% yields, respectively. Furthermore, 4 was treated with sodiomalonic ester to give diethyl 2-(naphtho[2,3-b ]furan-4,9-dione-2-yl)malonate (13) in 28% yield. Compound 13 was also obtained from the reactions of 5 and 7 with sodiomalonic ester. All t hese nucleophilic substitutions were carried out at room temperature. It was found that 4-7 had a high reactivity with various nucleophilic reagents.