Proton-exchanged montmorillonite-mediated reactions of hetero-benzyl acetates: Application to the synthesis of Zafirlukast

Proton-exchanged montmorillonite (H-mont) with outstanding surface characteristics can provide abundant acidic sites in the mesopores, and serve as an efficient heterogeneous catalyst for the synthesis of heterocycle-containing diarylmethanes via Friedel-Crafts-like alkylation of (hetero)arenes by heterobenzyl acetates under mild reaction conditions without requiring any additives or an inert atmosphere. Using this strategy, the gram-scale synthesis of indole-containing diarylmethane 13 has been accomplished in good yield for the preparation of Zafirlukast. In addition, H-mont can be applied to the nucleophilic substitution reactions of heterobenzyl acetate 5p with a variety of alcohols and 1,3-dicarbonyl compounds.