J. Koyanagi et al., NUCLEOPHILIC SUBSTITUTIONS OF 2-HALONAPHTHO[2,3-B]FURAN-4,9-DIONES AND 2-NITRONAPHTHO[2,3-B]FURAN-4,9-DIONE, Chemical and Pharmaceutical Bulletin, 45(10), 1997, pp. 1579-1581
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.