Biarylmethane and Fused Heterocyclic Arene Synthesis via in Situ Generated o- and/or p‑Naphthoquinone Methides

• Published in: Journal of organic chemistry 2015-06, Vol.80 (11), p.5556-5565
• Main Authors: Sawama, Yoshinari, Kawajiri, Takahiro, Asai, Shota, Yasukawa, Naoki, Shishido, Yuko, Monguchi, Yasunari, Sajiki, Hironao
• Format: Article
• Language: English
• ISSN: 0022-3263; 1520-6904
• DOI: 10.1021/acs.joc.5b00434

o- and/or p-naphthoquinone methides (NQMs) can be selectively prepared by the ring opening of 1-(siloxymethyl)-1,4-epoxy-1,4-dihydronaphthalene derivatives based on a substituent effect at the 4 position of the substrates. The 4-alkyl- or silyl-substituted 1-(siloxymethyl)-1,4-epoxy-1,4-dihydronaphthalene was transformed to o-NQM (1-naphthoquinone-2-methide), which underwent Friedel–Crafts 1,4-addition of the α,β-unsaturated carbonyl moiety to provide the 2-benzyl-1-naphthol as the biarylmethane and [4 + 2]-cycloaddition with a dienophile to give the fused heterocyclic arene. Meanwhile, the 4-unsubstituted 1-(siloxymethyl)-1,4-epoxy-1,4-dihydronaphthalene could be converted to the corresponding 4-benzyl-1-naphthol by the Friedel–Crafts 1,6-addition of p-NQM (1-naphthoquinone-4-methide) generated by the site-selective ring opening of the 1,4-epoxy moiety. Furthermore, the 4-(siloxymethyl)-(1,4-bis­(siloxymethyl))-1,4-epoxy-1,4-dihydronaphthalene was transformed into a 2,4-bisbenzyl-1-naphthol or pentacyclic derivative via both the o- and p-NQM intermediates.