Twin Benzoannulation of Naphthalene via 1,3-, 1,6-, and 2,6-Naphthodiyne Synthetic Equivalents. New Syntheses of Triphenylene, Benzanthracene, and Naphthacene

Article abstract of DOI:10.1021/jo00216a025

New syntheses of triphenylene (4), benzanthracene (5), naphthacene (6), and the tetramethylated derivatives 17 and 25 are described that feature, as the key step, the formal Diels-Alder cycloaddition between a naphthodiyne synthon (1, 2, or 3) and a furan (10 or 14).Subsequent deoxygenation affords the arene in 16-28percent overall yield from dibromo ditosylate 7, 8, or 9.The latter are prepared in two steps from commercially available 2,3- or 2,7-dihydroxynaphthalene, and, with phenyllithium, serve as synthetic equivalents of 1, 2, and 3.The X-ray structure of the anti isomer of 23 is discussed in some detail.