Regioselective condensation of hydroxyaromatic compounds with 2,5-dimethoxytetrahydrofuran: facile one-pot synthesis of new substituted diaryl-fused 2,8-dioxabicyclo[3.3.2]nonanes comprising central ketal moieties

Abstract

A tandem one-pot double Friedel–Crafts alkylation/intramolecular double cyclization process to conveniently assemble diaryl-fused 2,8-dioxabicyclo[3.3.2]nonanes with aryl substituents at the C-2 (β) position was developed. A series of new symmetrical 2,8-dioxabicyclo[3.3.2]nonanes fused with two phenyl and two naphthyl groups was synthesized through a straightforward, one-pot protocol based on a two-component regioselective condensation reaction starting from 2,5-dimethoxytetrahydrofuran, p-substituted phenols and 2-naphthol, respectively, using p-toluenesulfonic acid (PTSA) as a catalyst in methylene chloride in moderate to good yields, and various substitutions on one reaction partner were tolerated. Four chemical bonds (two C−C bonds and two C−O bonds) and two seven-membered cycles were formed in a one-pot operation. In the case of condensation of 2,7-dihydroxynaphthalene with 2,5-dimethoxytetrahydrofuran, 8,16-ethano-16H-dinaphtho[2,1-d:1′,2′-g][1,3]dioxocin-2,14-diol was obtained in good yield.